<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with Wdesk from Workiva-->
<!--Copyright 2022 Workiva-->
<!--r:0fdfc8fe-c699-42d5-9ee6-5d55fa379c25,g:5b8a5913-860e-4fd9-9e73-8f24afad39fc-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.harsco.com/role/CONSOLIDATEDSTATEMENTSOFOPERATIONS" xlink:type="simple" xlink:href="hsc-20211231.xsd#CONSOLIDATEDSTATEMENTSOFOPERATIONS"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/CONSOLIDATEDSTATEMENTSOFOPERATIONS" xlink:type="extended" id="i15a8194e38d34f38b96e3144b42cddfa_CONSOLIDATEDSTATEMENTSOFOPERATIONS">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_f7972146-4374-4668-86f4-708f832dba2a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesAbstract_a8a067e7-159f-43a3-b4b9-51a6af340db3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenuesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f7972146-4374-4668-86f4-708f832dba2a" xlink:to="loc_us-gaap_RevenuesAbstract_a8a067e7-159f-43a3-b4b9-51a6af340db3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_8ee3c54c-b1d6-49a0-8319-4d03d4842698" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_a8a067e7-159f-43a3-b4b9-51a6af340db3" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_8ee3c54c-b1d6-49a0-8319-4d03d4842698" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsAndExpensesAbstract_294696c4-a319-4b02-91a0-8c37c37d7e19" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CostsAndExpensesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f7972146-4374-4668-86f4-708f832dba2a" xlink:to="loc_us-gaap_CostsAndExpensesAbstract_294696c4-a319-4b02-91a0-8c37c37d7e19" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_53199dfb-19a8-4f0f-88f9-37419d4ad9d6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CostOfGoodsAndServicesSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_294696c4-a319-4b02-91a0-8c37c37d7e19" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_53199dfb-19a8-4f0f-88f9-37419d4ad9d6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpense_761697c6-1509-4c53-a36c-8f8500f86ac4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SellingGeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_294696c4-a319-4b02-91a0-8c37c37d7e19" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpense_761697c6-1509-4c53-a36c-8f8500f86ac4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_a3629dff-0283-49af-bec0-dbf56a1cffd8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ResearchAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_294696c4-a319-4b02-91a0-8c37c37d7e19" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_a3629dff-0283-49af-bec0-dbf56a1cffd8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherOperatingIncomeExpenseNet_5275b746-8e2a-4b54-8589-1eadcc25553f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherOperatingIncomeExpenseNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_294696c4-a319-4b02-91a0-8c37c37d7e19" xlink:to="loc_us-gaap_OtherOperatingIncomeExpenseNet_5275b746-8e2a-4b54-8589-1eadcc25553f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsAndExpenses_e30c675a-ef29-4d39-a84d-8b3e80c647c3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CostsAndExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_294696c4-a319-4b02-91a0-8c37c37d7e19" xlink:to="loc_us-gaap_CostsAndExpenses_e30c675a-ef29-4d39-a84d-8b3e80c647c3" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_746c50e7-a735-470a-b30d-b091eda35ba8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_294696c4-a319-4b02-91a0-8c37c37d7e19" xlink:to="loc_us-gaap_OperatingIncomeLoss_746c50e7-a735-470a-b30d-b091eda35ba8" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentIncomeInterest_b53f5ef3-e8e5-4e7b-aedb-2f1820608de6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InvestmentIncomeInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f7972146-4374-4668-86f4-708f832dba2a" xlink:to="loc_us-gaap_InvestmentIncomeInterest_b53f5ef3-e8e5-4e7b-aedb-2f1820608de6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_fc7759a1-9f3f-4f49-acc4-6737f5d6f4b0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f7972146-4374-4668-86f4-708f832dba2a" xlink:to="loc_us-gaap_InterestExpense_fc7759a1-9f3f-4f49-acc4-6737f5d6f4b0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionExpenseReversalOfExpenseNoncash_88cdf8af-f5f9-4c74-bdce-340e95bbb383" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PensionExpenseReversalOfExpenseNoncash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f7972146-4374-4668-86f4-708f832dba2a" xlink:to="loc_us-gaap_PensionExpenseReversalOfExpenseNoncash_88cdf8af-f5f9-4c74-bdce-340e95bbb383" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingExpense_3bb18851-6f36-4b4e-8e74-71a89c504c71" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherNonoperatingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f7972146-4374-4668-86f4-708f832dba2a" xlink:to="loc_us-gaap_OtherNonoperatingExpense_3bb18851-6f36-4b4e-8e74-71a89c504c71" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_30736631-de72-4dbb-af2a-d1e6cfa11361" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f7972146-4374-4668-86f4-708f832dba2a" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_30736631-de72-4dbb-af2a-d1e6cfa11361" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_28dffb39-26ce-475a-bbd0-0e49b0e3d003" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f7972146-4374-4668-86f4-708f832dba2a" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_28dffb39-26ce-475a-bbd0-0e49b0e3d003" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromEquityMethodInvestments_952888ca-b8eb-43f3-942a-7995897713c7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeLossFromEquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f7972146-4374-4668-86f4-708f832dba2a" xlink:to="loc_us-gaap_IncomeLossFromEquityMethodInvestments_952888ca-b8eb-43f3-942a-7995897713c7" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest_29835c59-125d-4611-b110-d43383126a90" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f7972146-4374-4668-86f4-708f832dba2a" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest_29835c59-125d-4611-b110-d43383126a90" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAbstract_c4fc1009-d602-4c86-888c-020ce2126c85" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f7972146-4374-4668-86f4-708f832dba2a" xlink:to="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAbstract_c4fc1009-d602-4c86-888c-020ce2126c85" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationBeforeIncomeTax_d8ef299a-ff2d-42ab-b1b9-4daf10140186" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationBeforeIncomeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAbstract_c4fc1009-d602-4c86-888c-020ce2126c85" xlink:to="loc_us-gaap_DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationBeforeIncomeTax_d8ef299a-ff2d-42ab-b1b9-4daf10140186" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax_678ecad3-66b0-478a-94ca-50621eee9038" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAbstract_c4fc1009-d602-4c86-888c-020ce2126c85" xlink:to="loc_us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax_678ecad3-66b0-478a-94ca-50621eee9038" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationTaxEffectOfDiscontinuedOperation_8be46af7-1cd9-4eca-90d6-886a82e846bc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DiscontinuedOperationTaxEffectOfDiscontinuedOperation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAbstract_c4fc1009-d602-4c86-888c-020ce2126c85" xlink:to="loc_us-gaap_DiscontinuedOperationTaxEffectOfDiscontinuedOperation_8be46af7-1cd9-4eca-90d6-886a82e846bc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity_30cd08a9-731e-467c-9789-8bd208712bd8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAbstract_c4fc1009-d602-4c86-888c-020ce2126c85" xlink:to="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity_30cd08a9-731e-467c-9789-8bd208712bd8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_d1860b36-708a-479e-bf5b-962fec71e54f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f7972146-4374-4668-86f4-708f832dba2a" xlink:to="loc_us-gaap_ProfitLoss_d1860b36-708a-479e-bf5b-962fec71e54f" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_86a9306a-5abd-45e1-bc3e-879a408f1e06" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetIncomeLossAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f7972146-4374-4668-86f4-708f832dba2a" xlink:to="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_86a9306a-5abd-45e1-bc3e-879a408f1e06" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_cf61e93c-c862-4b81-913e-9d308f39458b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f7972146-4374-4668-86f4-708f832dba2a" xlink:to="loc_us-gaap_NetIncomeLoss_cf61e93c-c862-4b81-913e-9d308f39458b" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeAmountsAttributableToReportingEntityDisclosuresAbstract_de886c28-3ede-4302-b07a-61997dc62573" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeAmountsAttributableToReportingEntityDisclosuresAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f7972146-4374-4668-86f4-708f832dba2a" xlink:to="loc_us-gaap_IncomeAmountsAttributableToReportingEntityDisclosuresAbstract_de886c28-3ede-4302-b07a-61997dc62573" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperations_092ecc40-19ff-4529-91e9-cf8f9e6b74f8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeLossFromContinuingOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeAmountsAttributableToReportingEntityDisclosuresAbstract_de886c28-3ede-4302-b07a-61997dc62573" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperations_092ecc40-19ff-4529-91e9-cf8f9e6b74f8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity_0eaff108-6bc9-47c6-9aa6-50ae4342bfcb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_465a5921-1119-4941-8bcf-6cfd8d58c219" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetIncomeLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_83d705ce-3ede-4115-be7f-ee60829cf7dc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f7972146-4374-4668-86f4-708f832dba2a" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_83d705ce-3ede-4115-be7f-ee60829cf7dc" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasicAbstract_ace04efe-a3ac-4f08-9059-982e26592317" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EarningsPerShareBasicAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f7972146-4374-4668-86f4-708f832dba2a" xlink:to="loc_us-gaap_EarningsPerShareBasicAbstract_ace04efe-a3ac-4f08-9059-982e26592317" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsPerBasicShare_b9c49a1b-7b35-4a3a-9064-0a068e0d08d0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsPerBasicShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_ace04efe-a3ac-4f08-9059-982e26592317" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsPerBasicShare_b9c49a1b-7b35-4a3a-9064-0a068e0d08d0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare_0904f81a-2044-47f6-b153-0a46f4ebff16" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_ace04efe-a3ac-4f08-9059-982e26592317" xlink:to="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare_0904f81a-2044-47f6-b153-0a46f4ebff16" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_2bda1798-ca01-45e0-b7fd-d65a9751bb9f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_ace04efe-a3ac-4f08-9059-982e26592317" xlink:to="loc_us-gaap_EarningsPerShareBasic_2bda1798-ca01-45e0-b7fd-d65a9751bb9f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_8d543f6f-3e55-4cfd-a293-99d425d6b67f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f7972146-4374-4668-86f4-708f832dba2a" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_8d543f6f-3e55-4cfd-a293-99d425d6b67f" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDilutedAbstract_3bc1cd9b-63b0-4e81-8b3d-9905a93bdcd9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EarningsPerShareDilutedAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f7972146-4374-4668-86f4-708f832dba2a" xlink:to="loc_us-gaap_EarningsPerShareDilutedAbstract_3bc1cd9b-63b0-4e81-8b3d-9905a93bdcd9" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare_4ba2cd50-837a-4aca-98be-5f67cb5e06cd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedAbstract_3bc1cd9b-63b0-4e81-8b3d-9905a93bdcd9" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare_4ba2cd50-837a-4aca-98be-5f67cb5e06cd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare_d27d86c1-13fa-452b-9f61-a7142eb3c373" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedAbstract_3bc1cd9b-63b0-4e81-8b3d-9905a93bdcd9" xlink:to="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare_d27d86c1-13fa-452b-9f61-a7142eb3c373" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_37076f91-3c94-44af-aa5f-044d35940be9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedAbstract_3bc1cd9b-63b0-4e81-8b3d-9905a93bdcd9" xlink:to="loc_us-gaap_EarningsPerShareDiluted_37076f91-3c94-44af-aa5f-044d35940be9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_793cea4d-d6f4-4919-8d62-f3925d21d381" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_f7972146-4374-4668-86f4-708f832dba2a" xlink:to="loc_us-gaap_StatementTable_793cea4d-d6f4-4919-8d62-f3925d21d381" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_c89001a8-9d87-4a86-a83f-691fbde8fdb7" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_793cea4d-d6f4-4919-8d62-f3925d21d381" xlink:to="loc_srt_ProductOrServiceAxis_c89001a8-9d87-4a86-a83f-691fbde8fdb7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_c89001a8-9d87-4a86-a83f-691fbde8fdb7_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_c89001a8-9d87-4a86-a83f-691fbde8fdb7" xlink:to="loc_srt_ProductsAndServicesDomain_c89001a8-9d87-4a86-a83f-691fbde8fdb7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_e6ea43ed-1315-4ea5-bd1b-c91b6968ad2c" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_c89001a8-9d87-4a86-a83f-691fbde8fdb7" xlink:to="loc_srt_ProductsAndServicesDomain_e6ea43ed-1315-4ea5-bd1b-c91b6968ad2c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServiceMember_c0beccca-e859-499c-88cf-774079ce9c82" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ServiceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_e6ea43ed-1315-4ea5-bd1b-c91b6968ad2c" xlink:to="loc_us-gaap_ServiceMember_c0beccca-e859-499c-88cf-774079ce9c82" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductMember_5865cd79-9f2a-4820-b95a-82319ec9de81" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProductMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_e6ea43ed-1315-4ea5-bd1b-c91b6968ad2c" xlink:to="loc_us-gaap_ProductMember_5865cd79-9f2a-4820-b95a-82319ec9de81" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/CONSOLIDATEDSTATEMENTSOFCHANGESINEQUITY" xlink:type="simple" xlink:href="hsc-20211231.xsd#CONSOLIDATEDSTATEMENTSOFCHANGESINEQUITY"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/CONSOLIDATEDSTATEMENTSOFCHANGESINEQUITY" xlink:type="extended" id="i7c706df440d64ca6a16ab6aa694ec66e_CONSOLIDATEDSTATEMENTSOFCHANGESINEQUITY">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_7af19dfb-481b-4b52-a12c-a2e246df0fde" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_f108dfa4-6574-4cde-9937-92dd03c6a61d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_7af19dfb-481b-4b52-a12c-a2e246df0fde" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_f108dfa4-6574-4cde-9937-92dd03c6a61d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_0fade92d-3efc-417b-a9ec-cbf9e4098a3f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_f108dfa4-6574-4cde-9937-92dd03c6a61d" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_0fade92d-3efc-417b-a9ec-cbf9e4098a3f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_043fece3-9900-4b3c-bbdc-65b3dd3ee4e9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_f108dfa4-6574-4cde-9937-92dd03c6a61d" xlink:to="loc_us-gaap_ProfitLoss_043fece3-9900-4b3c-bbdc-65b3dd3ee4e9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsCommonStockAbstract_1b7ad21d-6d9d-498a-bbb2-2d155a091450" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DividendsCommonStockAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_f108dfa4-6574-4cde-9937-92dd03c6a61d" xlink:to="loc_us-gaap_DividendsCommonStockAbstract_1b7ad21d-6d9d-498a-bbb2-2d155a091450" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_2d7cd3a1-20ba-490b-8e88-6c74c613dc64" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DividendsCommonStockAbstract_1b7ad21d-6d9d-498a-bbb2-2d155a091450" xlink:to="loc_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_2d7cd3a1-20ba-490b-8e88-6c74c613dc64" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_2df84af3-f22f-4403-b3ec-6f78cfa1f6e9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_f108dfa4-6574-4cde-9937-92dd03c6a61d" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_2df84af3-f22f-4403-b3ec-6f78cfa1f6e9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_PurchaseOfNoncontrollingInterest_b83c2bb1-d9b9-4c1a-90a6-ac69c20fb355" xlink:href="hsc-20211231.xsd#hsc_PurchaseOfNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_f108dfa4-6574-4cde-9937-92dd03c6a61d" xlink:to="loc_hsc_PurchaseOfNoncontrollingInterest_b83c2bb1-d9b9-4c1a-90a6-ac69c20fb355" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestIncreaseFromSaleOfParentEquityInterest_a8f0bb1f-dd68-455f-9cbd-dc416ada1e68" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NoncontrollingInterestIncreaseFromSaleOfParentEquityInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_f108dfa4-6574-4cde-9937-92dd03c6a61d" xlink:to="loc_us-gaap_NoncontrollingInterestIncreaseFromSaleOfParentEquityInterest_a8f0bb1f-dd68-455f-9cbd-dc416ada1e68" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestDecreaseFromDeconsolidation_5d844965-e01b-4e18-a507-d7eb3a6cb164" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NoncontrollingInterestDecreaseFromDeconsolidation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_f108dfa4-6574-4cde-9937-92dd03c6a61d" xlink:to="loc_us-gaap_NoncontrollingInterestDecreaseFromDeconsolidation_5d844965-e01b-4e18-a507-d7eb3a6cb164" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueOther_e865786b-2dad-4e60-ae9e-3cd2ac1a3c09" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_f108dfa4-6574-4cde-9937-92dd03c6a61d" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueOther_e865786b-2dad-4e60-ae9e-3cd2ac1a3c09" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures_74b8f2a1-671b-4df5-8010-c7404f5eb887" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_f108dfa4-6574-4cde-9937-92dd03c6a61d" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures_74b8f2a1-671b-4df5-8010-c7404f5eb887" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_VestingofPerformanceShareUnits_14c5292d-92fb-4724-ba26-0e47c03d678e" xlink:href="hsc-20211231.xsd#hsc_VestingofPerformanceShareUnits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_f108dfa4-6574-4cde-9937-92dd03c6a61d" xlink:to="loc_hsc_VestingofPerformanceShareUnits_14c5292d-92fb-4724-ba26-0e47c03d678e" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_f577cb27-1933-43a6-bec5-83521630ce65" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_f108dfa4-6574-4cde-9937-92dd03c6a61d" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_f577cb27-1933-43a6-bec5-83521630ce65" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_669321a6-d86a-40b0-becc-f835cc3b718a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_f108dfa4-6574-4cde-9937-92dd03c6a61d" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_669321a6-d86a-40b0-becc-f835cc3b718a" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_bba1c599-70b3-449c-9bce-097c8eaf9e83" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_1f4d94be-ee74-4e99-9d56-854678e52f93" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_7af19dfb-481b-4b52-a12c-a2e246df0fde" xlink:to="loc_us-gaap_StatementTable_1f4d94be-ee74-4e99-9d56-854678e52f93" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_e4836f63-95ca-462b-881a-ccfd3ad53de0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_1f4d94be-ee74-4e99-9d56-854678e52f93" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_e4836f63-95ca-462b-881a-ccfd3ad53de0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_e4836f63-95ca-462b-881a-ccfd3ad53de0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_e4836f63-95ca-462b-881a-ccfd3ad53de0" xlink:to="loc_us-gaap_EquityComponentDomain_e4836f63-95ca-462b-881a-ccfd3ad53de0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_d7b48f15-f2fd-49af-9c7d-3e0ae8ecaff4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_e4836f63-95ca-462b-881a-ccfd3ad53de0" xlink:to="loc_us-gaap_EquityComponentDomain_d7b48f15-f2fd-49af-9c7d-3e0ae8ecaff4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_3ddc4057-df8c-4754-b12d-2c6338125ba3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_d7b48f15-f2fd-49af-9c7d-3e0ae8ecaff4" xlink:to="loc_us-gaap_CommonStockMember_3ddc4057-df8c-4754-b12d-2c6338125ba3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockMember_44b35558-e287-4c2a-833c-f97d9dbf33fc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TreasuryStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_d7b48f15-f2fd-49af-9c7d-3e0ae8ecaff4" xlink:to="loc_us-gaap_TreasuryStockMember_44b35558-e287-4c2a-833c-f97d9dbf33fc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_145a35d7-3bde-4359-8217-8ccc948f32f8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_d7b48f15-f2fd-49af-9c7d-3e0ae8ecaff4" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_145a35d7-3bde-4359-8217-8ccc948f32f8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_a4e1799a-f910-45a8-bc91-135d15f011e3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_d7b48f15-f2fd-49af-9c7d-3e0ae8ecaff4" xlink:to="loc_us-gaap_RetainedEarningsMember_a4e1799a-f910-45a8-bc91-135d15f011e3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_491fd5ea-2164-413b-9c22-bf402c22b0f1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_d7b48f15-f2fd-49af-9c7d-3e0ae8ecaff4" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_491fd5ea-2164-413b-9c22-bf402c22b0f1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestMember_f358f315-d3fc-49e5-9ce9-98808653cca2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_d7b48f15-f2fd-49af-9c7d-3e0ae8ecaff4" xlink:to="loc_us-gaap_NoncontrollingInterestMember_f358f315-d3fc-49e5-9ce9-98808653cca2" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_a53ba368-91b2-4e27-b6cd-112e5f96bda3" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_1f4d94be-ee74-4e99-9d56-854678e52f93" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_a53ba368-91b2-4e27-b6cd-112e5f96bda3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_a53ba368-91b2-4e27-b6cd-112e5f96bda3_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_a53ba368-91b2-4e27-b6cd-112e5f96bda3" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_a53ba368-91b2-4e27-b6cd-112e5f96bda3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_a42f0abb-447e-49a8-a0f5-19e75ab9154d" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_a53ba368-91b2-4e27-b6cd-112e5f96bda3" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_a42f0abb-447e-49a8-a0f5-19e75ab9154d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember_234909af-abda-43aa-bcee-f94d5e8b57b5" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_a42f0abb-447e-49a8-a0f5-19e75ab9154d" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember_234909af-abda-43aa-bcee-f94d5e8b57b5" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/CONSOLIDATEDSTATEMENTSOFCHANGESINEQUITYParenthetical" xlink:type="simple" xlink:href="hsc-20211231.xsd#CONSOLIDATEDSTATEMENTSOFCHANGESINEQUITYParenthetical"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/CONSOLIDATEDSTATEMENTSOFCHANGESINEQUITYParenthetical" xlink:type="extended" id="i1995afe93ea64bf99cba24f5494d9a48_CONSOLIDATEDSTATEMENTSOFCHANGESINEQUITYParenthetical">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_fe8aee2f-cae8-4ed9-8c87-d54e00a416a8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossTax_e8748d01-1e0d-4e31-9664-f7766320c5b5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_fe8aee2f-cae8-4ed9-8c87-d54e00a416a8" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossTax_e8748d01-1e0d-4e31-9664-f7766320c5b5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised_f8c4b4af-4f05-4b8a-bb24-5c8431e8cdc4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_fe8aee2f-cae8-4ed9-8c87-d54e00a416a8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised_f8c4b4af-4f05-4b8a-bb24-5c8431e8cdc4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeituresAndTaxObligationsSettledInShares_e684a4ac-dedf-4c3e-8ed2-223f2693d968" xlink:href="hsc-20211231.xsd#hsc_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeituresAndTaxObligationsSettledInShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_fe8aee2f-cae8-4ed9-8c87-d54e00a416a8" xlink:to="loc_hsc_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeituresAndTaxObligationsSettledInShares_e684a4ac-dedf-4c3e-8ed2-223f2693d968" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_VestingofPerformanceShares_136bd743-9ccb-42fa-9a8d-31ab4bf42639" xlink:href="hsc-20211231.xsd#hsc_VestingofPerformanceShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_fe8aee2f-cae8-4ed9-8c87-d54e00a416a8" xlink:to="loc_hsc_VestingofPerformanceShares_136bd743-9ccb-42fa-9a8d-31ab4bf42639" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_924783db-375c-4bc8-aa68-e6165f55a7ee" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TreasuryStockSharesAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_fe8aee2f-cae8-4ed9-8c87-d54e00a416a8" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_924783db-375c-4bc8-aa68-e6165f55a7ee" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_39a647b9-e655-4950-9647-e9242e7b8871" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_fe8aee2f-cae8-4ed9-8c87-d54e00a416a8" xlink:to="loc_us-gaap_StatementTable_39a647b9-e655-4950-9647-e9242e7b8871" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_f8a854b3-d0a3-4d8b-a41d-dd4619651a2b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_39a647b9-e655-4950-9647-e9242e7b8871" xlink:to="loc_us-gaap_StatementClassOfStockAxis_f8a854b3-d0a3-4d8b-a41d-dd4619651a2b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_f8a854b3-d0a3-4d8b-a41d-dd4619651a2b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_f8a854b3-d0a3-4d8b-a41d-dd4619651a2b" xlink:to="loc_us-gaap_ClassOfStockDomain_f8a854b3-d0a3-4d8b-a41d-dd4619651a2b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_31f286bf-467d-4594-80df-322e20e7bd16" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_f8a854b3-d0a3-4d8b-a41d-dd4619651a2b" xlink:to="loc_us-gaap_ClassOfStockDomain_31f286bf-467d-4594-80df-322e20e7bd16" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockMember_0f2b8971-f4e4-4666-a893-78e2d87855b4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TreasuryStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_31f286bf-467d-4594-80df-322e20e7bd16" xlink:to="loc_us-gaap_TreasuryStockMember_0f2b8971-f4e4-4666-a893-78e2d87855b4" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/SummaryofSignificantAccountingPoliciesDetails3" xlink:type="simple" xlink:href="hsc-20211231.xsd#SummaryofSignificantAccountingPoliciesDetails3"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/SummaryofSignificantAccountingPoliciesDetails3" xlink:type="extended" id="i588608a79719493f9413c47e88a9a84c_SummaryofSignificantAccountingPoliciesDetails3">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_397b5bf3-8ea5-4f4c-a29b-553bd3274433" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualProvision_22020e34-e4b9-408d-bb81-7e028c563fd6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LossContingencyAccrualProvision"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_397b5bf3-8ea5-4f4c-a29b-553bd3274433" xlink:to="loc_us-gaap_LossContingencyAccrualProvision_22020e34-e4b9-408d-bb81-7e028c563fd6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_LossContingencyAccrualRetrospectiveAdjustment_39268c87-df0f-49a2-b046-36c0ee872ecb" xlink:href="hsc-20211231.xsd#hsc_LossContingencyAccrualRetrospectiveAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_397b5bf3-8ea5-4f4c-a29b-553bd3274433" xlink:to="loc_hsc_LossContingencyAccrualRetrospectiveAdjustment_39268c87-df0f-49a2-b046-36c0ee872ecb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualAtCarryingValue_5da27c19-ab59-4d0b-9ac8-5e050257460e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LossContingencyAccrualAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_397b5bf3-8ea5-4f4c-a29b-553bd3274433" xlink:to="loc_us-gaap_LossContingencyAccrualAtCarryingValue_5da27c19-ab59-4d0b-9ac8-5e050257460e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyReceivable_2a158b49-33b7-494b-9dfb-335c574b8b6d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LossContingencyReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_397b5bf3-8ea5-4f4c-a29b-553bd3274433" xlink:to="loc_us-gaap_LossContingencyReceivable_2a158b49-33b7-494b-9dfb-335c574b8b6d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_7c521d70-b479-4c75-82ed-9d782570c967" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_397b5bf3-8ea5-4f4c-a29b-553bd3274433" xlink:to="loc_us-gaap_LossContingenciesTable_7c521d70-b479-4c75-82ed-9d782570c967" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_5c943427-decb-42b8-85b2-939244e1811c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_7c521d70-b479-4c75-82ed-9d782570c967" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_5c943427-decb-42b8-85b2-939244e1811c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_5c943427-decb-42b8-85b2-939244e1811c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_5c943427-decb-42b8-85b2-939244e1811c" xlink:to="loc_us-gaap_LossContingencyNatureDomain_5c943427-decb-42b8-85b2-939244e1811c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_cb3fd670-295e-4055-9850-071c51a69ec8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_5c943427-decb-42b8-85b2-939244e1811c" xlink:to="loc_us-gaap_LossContingencyNatureDomain_cb3fd670-295e-4055-9850-071c51a69ec8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UninsuredRiskMember_cf58fe20-d655-41dd-b920-0b4ce49ad7ce" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_UninsuredRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_cb3fd670-295e-4055-9850-071c51a69ec8" xlink:to="loc_us-gaap_UninsuredRiskMember_cf58fe20-d655-41dd-b920-0b4ce49ad7ce" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/SummaryofSignificantAccountingPoliciesDetails4" xlink:type="simple" xlink:href="hsc-20211231.xsd#SummaryofSignificantAccountingPoliciesDetails4"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/SummaryofSignificantAccountingPoliciesDetails4" xlink:type="extended" id="i0d41656cd5794d92bead3d2b98be9dd8_SummaryofSignificantAccountingPoliciesDetails4">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_2f1cad6b-3742-469e-8125-577abc205cff" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_60bd65cb-7605-4670-a3f1-64e51443a1d8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_2f1cad6b-3742-469e-8125-577abc205cff" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_60bd65cb-7605-4670-a3f1-64e51443a1d8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DerivativeMaturityPeriod_def54184-b268-4895-9f56-d8b78347997e" xlink:href="hsc-20211231.xsd#hsc_DerivativeMaturityPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_2f1cad6b-3742-469e-8125-577abc205cff" xlink:to="loc_hsc_DerivativeMaturityPeriod_def54184-b268-4895-9f56-d8b78347997e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_4d288fd0-5ce9-4d9a-85ba-1c49d6867e4a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_2f1cad6b-3742-469e-8125-577abc205cff" xlink:to="loc_us-gaap_DerivativeTable_4d288fd0-5ce9-4d9a-85ba-1c49d6867e4a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_fa780cae-dc49-4545-b47f-73b2f6681f6b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_4d288fd0-5ce9-4d9a-85ba-1c49d6867e4a" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_fa780cae-dc49-4545-b47f-73b2f6681f6b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_fa780cae-dc49-4545-b47f-73b2f6681f6b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_fa780cae-dc49-4545-b47f-73b2f6681f6b" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_fa780cae-dc49-4545-b47f-73b2f6681f6b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_4b5b5b17-2f4e-491d-8999-ffb9b0b355e5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_fa780cae-dc49-4545-b47f-73b2f6681f6b" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_4b5b5b17-2f4e-491d-8999-ffb9b0b355e5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeForwardMember_47dc917a-ce79-404a-a62e-ea795e2208d5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ForeignExchangeForwardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_4b5b5b17-2f4e-491d-8999-ffb9b0b355e5" xlink:to="loc_us-gaap_ForeignExchangeForwardMember_47dc917a-ce79-404a-a62e-ea795e2208d5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_4b36aaeb-cf55-4c3b-9d84-918a30c03bf3" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_4d288fd0-5ce9-4d9a-85ba-1c49d6867e4a" xlink:to="loc_srt_RangeAxis_4b36aaeb-cf55-4c3b-9d84-918a30c03bf3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_4b36aaeb-cf55-4c3b-9d84-918a30c03bf3_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_4b36aaeb-cf55-4c3b-9d84-918a30c03bf3" xlink:to="loc_srt_RangeMember_4b36aaeb-cf55-4c3b-9d84-918a30c03bf3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_48a60809-84ce-40b0-a6ef-9beb86928825" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_4b36aaeb-cf55-4c3b-9d84-918a30c03bf3" xlink:to="loc_srt_RangeMember_48a60809-84ce-40b0-a6ef-9beb86928825" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_9646a7f6-a3c9-4ffb-b11a-7ab3aab3436d" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_48a60809-84ce-40b0-a6ef-9beb86928825" xlink:to="loc_srt_MaximumMember_9646a7f6-a3c9-4ffb-b11a-7ab3aab3436d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_1ef796f5-05d2-463f-b5e5-81885debe765" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_4d288fd0-5ce9-4d9a-85ba-1c49d6867e4a" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_1ef796f5-05d2-463f-b5e5-81885debe765" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_1ef796f5-05d2-463f-b5e5-81885debe765_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_1ef796f5-05d2-463f-b5e5-81885debe765" xlink:to="loc_us-gaap_SegmentDomain_1ef796f5-05d2-463f-b5e5-81885debe765_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_c1ca4720-0553-4cbb-915a-b7b64c68afc3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_1ef796f5-05d2-463f-b5e5-81885debe765" xlink:to="loc_us-gaap_SegmentDomain_c1ca4720-0553-4cbb-915a-b7b64c68afc3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoRailMember_f183767c-09a0-4c63-ab9b-dc503118eb0f" xlink:href="hsc-20211231.xsd#hsc_HarscoRailMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_c1ca4720-0553-4cbb-915a-b7b64c68afc3" xlink:to="loc_hsc_HarscoRailMember_f183767c-09a0-4c63-ab9b-dc503118eb0f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_3c5fc306-1d9e-4248-9d36-27cbb381ec8e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TimingOfTransferOfGoodOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_4d288fd0-5ce9-4d9a-85ba-1c49d6867e4a" xlink:to="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_3c5fc306-1d9e-4248-9d36-27cbb381ec8e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_3c5fc306-1d9e-4248-9d36-27cbb381ec8e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TimingOfTransferOfGoodOrServiceDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_3c5fc306-1d9e-4248-9d36-27cbb381ec8e" xlink:to="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_3c5fc306-1d9e-4248-9d36-27cbb381ec8e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_3fc5fa3e-1fe5-4303-82eb-022320bc56d8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TimingOfTransferOfGoodOrServiceDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_3c5fc306-1d9e-4248-9d36-27cbb381ec8e" xlink:to="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_3fc5fa3e-1fe5-4303-82eb-022320bc56d8" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/AcquisitionsandDispositionsScheduleofBalanceSheetfromDisposalofHarscoRailSegmentDetailsDetails" xlink:type="simple" xlink:href="hsc-20211231.xsd#AcquisitionsandDispositionsScheduleofBalanceSheetfromDisposalofHarscoRailSegmentDetailsDetails"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/AcquisitionsandDispositionsScheduleofBalanceSheetfromDisposalofHarscoRailSegmentDetailsDetails" xlink:type="extended" id="i0efe5acabdc84b6a87bd72fa411aa2f9_AcquisitionsandDispositionsScheduleofBalanceSheetfromDisposalofHarscoRailSegmentDetailsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_476a698b-9558-4b19-8db7-98af840f7910" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DisposalGroupIncludingDiscontinuedOperationTradeAccountsReceivable_b46eba9c-6ce5-4b6e-990c-72b6616ce541" xlink:href="hsc-20211231.xsd#hsc_DisposalGroupIncludingDiscontinuedOperationTradeAccountsReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_476a698b-9558-4b19-8db7-98af840f7910" xlink:to="loc_hsc_DisposalGroupIncludingDiscontinuedOperationTradeAccountsReceivable_b46eba9c-6ce5-4b6e-990c-72b6616ce541" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DisposalGroupIncludingDiscontinuedOperationOtherReceivablesCurrent_aa1b9c0e-b91c-4a65-bc1a-c9de4e649c70" xlink:href="hsc-20211231.xsd#hsc_DisposalGroupIncludingDiscontinuedOperationOtherReceivablesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_476a698b-9558-4b19-8db7-98af840f7910" xlink:to="loc_hsc_DisposalGroupIncludingDiscontinuedOperationOtherReceivablesCurrent_aa1b9c0e-b91c-4a65-bc1a-c9de4e649c70" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationInventoryCurrent_5a2b51c2-360a-4172-a0d7-67f72358f854" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationInventoryCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_476a698b-9558-4b19-8db7-98af840f7910" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationInventoryCurrent_5a2b51c2-360a-4172-a0d7-67f72358f854" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DisposalGroupIncludingDiscontinuedOperationContractAssetCurrent_b2aec51f-2498-4fda-b929-e36f684b34d6" xlink:href="hsc-20211231.xsd#hsc_DisposalGroupIncludingDiscontinuedOperationContractAssetCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_476a698b-9558-4b19-8db7-98af840f7910" xlink:to="loc_hsc_DisposalGroupIncludingDiscontinuedOperationContractAssetCurrent_b2aec51f-2498-4fda-b929-e36f684b34d6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherCurrentAssets_83ad866d-9840-4a04-85a8-bb2dca6bd716" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherCurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_476a698b-9558-4b19-8db7-98af840f7910" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherCurrentAssets_83ad866d-9840-4a04-85a8-bb2dca6bd716" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentNoncurrent_1e3cf928-06e0-4bb1-894c-5cf14a4e7c3b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_476a698b-9558-4b19-8db7-98af840f7910" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentNoncurrent_1e3cf928-06e0-4bb1-894c-5cf14a4e7c3b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DisposalGroupIncludingDiscontinuedOperationOperatingLeaseRightOfUseAsset_85d5cfe0-a439-43c2-a971-e6b230487001" xlink:href="hsc-20211231.xsd#hsc_DisposalGroupIncludingDiscontinuedOperationOperatingLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_476a698b-9558-4b19-8db7-98af840f7910" xlink:to="loc_hsc_DisposalGroupIncludingDiscontinuedOperationOperatingLeaseRightOfUseAsset_85d5cfe0-a439-43c2-a971-e6b230487001" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationGoodwill1_ac7b4101-9eec-447d-a2c7-7c99f74811f2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationGoodwill1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_476a698b-9558-4b19-8db7-98af840f7910" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationGoodwill1_ac7b4101-9eec-447d-a2c7-7c99f74811f2" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationIntangibleAssetsNoncurrent_9184aec3-40eb-4c06-8e03-a1d9abffd338" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationIntangibleAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_476a698b-9558-4b19-8db7-98af840f7910" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationIntangibleAssetsNoncurrent_9184aec3-40eb-4c06-8e03-a1d9abffd338" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationDeferredTaxAssets_dbd01bad-3632-4634-b8f4-54c815b4f596" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationDeferredTaxAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_476a698b-9558-4b19-8db7-98af840f7910" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationDeferredTaxAssets_dbd01bad-3632-4634-b8f4-54c815b4f596" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentAssets_41c3058f-f077-4e9a-89b9-1adb244ebbb1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_476a698b-9558-4b19-8db7-98af840f7910" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentAssets_41c3058f-f077-4e9a-89b9-1adb244ebbb1" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation_692994cf-0813-4047-8edd-033d56856027" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_476a698b-9558-4b19-8db7-98af840f7910" xlink:to="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation_692994cf-0813-4047-8edd-033d56856027" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsPayable_d2316657-284b-48b4-b837-6cff0a3a6729" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_476a698b-9558-4b19-8db7-98af840f7910" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsPayable_d2316657-284b-48b4-b837-6cff0a3a6729" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DisposalGroupIncludingDiscontinuedOperationEmployeeRelatedLiabilitiesCurrent_c618c61c-615d-44dd-88e9-bf661259ffcc" xlink:href="hsc-20211231.xsd#hsc_DisposalGroupIncludingDiscontinuedOperationEmployeeRelatedLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_476a698b-9558-4b19-8db7-98af840f7910" xlink:to="loc_hsc_DisposalGroupIncludingDiscontinuedOperationEmployeeRelatedLiabilitiesCurrent_c618c61c-615d-44dd-88e9-bf661259ffcc" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DisposalGroupIncludingDiscontinuedOperationOperatingLeaseLiabilityCurrent_98acf08c-e576-417f-9f62-fd8e2baadc35" xlink:href="hsc-20211231.xsd#hsc_DisposalGroupIncludingDiscontinuedOperationOperatingLeaseLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_476a698b-9558-4b19-8db7-98af840f7910" xlink:to="loc_hsc_DisposalGroupIncludingDiscontinuedOperationOperatingLeaseLiabilityCurrent_98acf08c-e576-417f-9f62-fd8e2baadc35" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DisposalGroupIncludingDiscontinuedOperationOtherLiabilityCurrent_29bf9c65-ef70-4454-98a4-7c5c00740e1f" xlink:href="hsc-20211231.xsd#hsc_DisposalGroupIncludingDiscontinuedOperationOtherLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_476a698b-9558-4b19-8db7-98af840f7910" xlink:to="loc_hsc_DisposalGroupIncludingDiscontinuedOperationOtherLiabilityCurrent_29bf9c65-ef70-4454-98a4-7c5c00740e1f" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DisposalGroupIncludingDiscontinuedOperationAdvanceOnContractNoncurrent_7c00f1eb-7b25-4dd4-a5a7-b8569c2485d5" xlink:href="hsc-20211231.xsd#hsc_DisposalGroupIncludingDiscontinuedOperationAdvanceOnContractNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_476a698b-9558-4b19-8db7-98af840f7910" xlink:to="loc_hsc_DisposalGroupIncludingDiscontinuedOperationAdvanceOnContractNoncurrent_7c00f1eb-7b25-4dd4-a5a7-b8569c2485d5" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DisposalGroupIncludingDiscontinuedOperationAdvanceOnContract_1c6d3fc6-0b41-4f73-b44b-d68890c5e42a" xlink:href="hsc-20211231.xsd#hsc_DisposalGroupIncludingDiscontinuedOperationAdvanceOnContract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_476a698b-9558-4b19-8db7-98af840f7910" xlink:to="loc_hsc_DisposalGroupIncludingDiscontinuedOperationAdvanceOnContract_1c6d3fc6-0b41-4f73-b44b-d68890c5e42a" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationDeferredTaxLiabilities_0117a9a5-5dd4-4fa1-b6d0-5d7975c5d021" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationDeferredTaxLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_476a698b-9558-4b19-8db7-98af840f7910" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationDeferredTaxLiabilities_0117a9a5-5dd4-4fa1-b6d0-5d7975c5d021" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DisposalGroupIncludingDiscontinuedOperationOperatingLeaseLiabilityNoncurrent_bf5fab57-a951-49ab-9ff2-9eaad46571c6" xlink:href="hsc-20211231.xsd#hsc_DisposalGroupIncludingDiscontinuedOperationOperatingLeaseLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_476a698b-9558-4b19-8db7-98af840f7910" xlink:to="loc_hsc_DisposalGroupIncludingDiscontinuedOperationOperatingLeaseLiabilityNoncurrent_bf5fab57-a951-49ab-9ff2-9eaad46571c6" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherLiabilities_911330d0-aa78-4f87-8cca-b28556f7f9be" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_476a698b-9558-4b19-8db7-98af840f7910" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherLiabilities_911330d0-aa78-4f87-8cca-b28556f7f9be" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation_524fe587-6e08-4df2-8a8d-1aef4f38a62c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_476a698b-9558-4b19-8db7-98af840f7910" xlink:to="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation_524fe587-6e08-4df2-8a8d-1aef4f38a62c" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_1a1ae6b8-82e2-4782-a696-8470e0232df1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_476a698b-9558-4b19-8db7-98af840f7910" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_1a1ae6b8-82e2-4782-a696-8470e0232df1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_9aa143e0-2a8d-4938-99cf-ff5b65b37bde" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_1a1ae6b8-82e2-4782-a696-8470e0232df1" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_9aa143e0-2a8d-4938-99cf-ff5b65b37bde" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_9aa143e0-2a8d-4938-99cf-ff5b65b37bde_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_9aa143e0-2a8d-4938-99cf-ff5b65b37bde" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_9aa143e0-2a8d-4938-99cf-ff5b65b37bde_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_5dc584bf-32be-4c45-8198-b95388b8b272" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_9aa143e0-2a8d-4938-99cf-ff5b65b37bde" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_5dc584bf-32be-4c45-8198-b95388b8b272" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationsHeldforsaleMember_0406245f-ab76-4fd0-8b6a-e4e1d24e659c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DiscontinuedOperationsHeldforsaleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_5dc584bf-32be-4c45-8198-b95388b8b272" xlink:to="loc_us-gaap_DiscontinuedOperationsHeldforsaleMember_0406245f-ab76-4fd0-8b6a-e4e1d24e659c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_1b832930-e94c-449a-8249-c171ef97e8ed" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_1a1ae6b8-82e2-4782-a696-8470e0232df1" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_1b832930-e94c-449a-8249-c171ef97e8ed" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_1b832930-e94c-449a-8249-c171ef97e8ed_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_1b832930-e94c-449a-8249-c171ef97e8ed" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_1b832930-e94c-449a-8249-c171ef97e8ed_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_20f19910-88f8-4bcb-aab2-e3b99fc85c8d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_1b832930-e94c-449a-8249-c171ef97e8ed" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_20f19910-88f8-4bcb-aab2-e3b99fc85c8d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoRailMember_a049867a-7f1d-457f-b331-60564c7579a3" xlink:href="hsc-20211231.xsd#hsc_HarscoRailMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_20f19910-88f8-4bcb-aab2-e3b99fc85c8d" xlink:to="loc_hsc_HarscoRailMember_a049867a-7f1d-457f-b331-60564c7579a3" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/AcquisitionsandDispositionsScheduleofIncomeLossfromDiscontinuedOperationsHarscoRailDetails" xlink:type="simple" xlink:href="hsc-20211231.xsd#AcquisitionsandDispositionsScheduleofIncomeLossfromDiscontinuedOperationsHarscoRailDetails"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/AcquisitionsandDispositionsScheduleofIncomeLossfromDiscontinuedOperationsHarscoRailDetails" xlink:type="extended" id="i0c2b1b487a944f169af1dd6c678f4d8c_AcquisitionsandDispositionsScheduleofIncomeLossfromDiscontinuedOperationsHarscoRailDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_c360d9d5-0ebc-455f-b520-47520fe28fd5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue_34fcf77b-dda9-4f5d-be58-40928ae5df20" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_c360d9d5-0ebc-455f-b520-47520fe28fd5" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue_34fcf77b-dda9-4f5d-be58-40928ae5df20" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationCostsOfGoodsSold_a54e0f78-e925-4946-bb46-e8af243511ee" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationCostsOfGoodsSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_c360d9d5-0ebc-455f-b520-47520fe28fd5" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationCostsOfGoodsSold_a54e0f78-e925-4946-bb46-e8af243511ee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax_ee427e42-f5c8-4c47-920d-75b87381e5f5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_c360d9d5-0ebc-455f-b520-47520fe28fd5" xlink:to="loc_us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax_ee427e42-f5c8-4c47-920d-75b87381e5f5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationGeneralAndAdministrativeExpense_14c53fc5-1c9d-4174-b562-7691fcc3854a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationGeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_c360d9d5-0ebc-455f-b520-47520fe28fd5" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationGeneralAndAdministrativeExpense_14c53fc5-1c9d-4174-b562-7691fcc3854a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_fdd9f1c6-7c53-44a7-9f3f-08560667afc9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_c360d9d5-0ebc-455f-b520-47520fe28fd5" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_fdd9f1c6-7c53-44a7-9f3f-08560667afc9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_4b3746ba-294b-4e7c-b58b-959632266653" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_fdd9f1c6-7c53-44a7-9f3f-08560667afc9" xlink:to="loc_srt_ProductOrServiceAxis_4b3746ba-294b-4e7c-b58b-959632266653" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_4b3746ba-294b-4e7c-b58b-959632266653_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_4b3746ba-294b-4e7c-b58b-959632266653" xlink:to="loc_srt_ProductsAndServicesDomain_4b3746ba-294b-4e7c-b58b-959632266653_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_5948068e-66b1-4316-a24f-b17c89044f75" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_4b3746ba-294b-4e7c-b58b-959632266653" xlink:to="loc_srt_ProductsAndServicesDomain_5948068e-66b1-4316-a24f-b17c89044f75" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServiceMember_bcb95be5-b984-4626-babe-28824f62a33e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ServiceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_5948068e-66b1-4316-a24f-b17c89044f75" xlink:to="loc_us-gaap_ServiceMember_bcb95be5-b984-4626-babe-28824f62a33e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductMember_467076cd-35c5-4ea5-8594-55957cbaa254" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProductMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_5948068e-66b1-4316-a24f-b17c89044f75" xlink:to="loc_us-gaap_ProductMember_467076cd-35c5-4ea5-8594-55957cbaa254" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_4eb3662b-c28c-4269-a09e-7155c5e44ddc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_fdd9f1c6-7c53-44a7-9f3f-08560667afc9" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_4eb3662b-c28c-4269-a09e-7155c5e44ddc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_4eb3662b-c28c-4269-a09e-7155c5e44ddc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_4eb3662b-c28c-4269-a09e-7155c5e44ddc" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_4eb3662b-c28c-4269-a09e-7155c5e44ddc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_2a3ff711-3c01-42f9-a999-7ef680269f0c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_4eb3662b-c28c-4269-a09e-7155c5e44ddc" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_2a3ff711-3c01-42f9-a999-7ef680269f0c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationsHeldforsaleMember_2d0d1672-959a-4d85-99b0-0c1d7ed131cd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DiscontinuedOperationsHeldforsaleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_2a3ff711-3c01-42f9-a999-7ef680269f0c" xlink:to="loc_us-gaap_DiscontinuedOperationsHeldforsaleMember_2d0d1672-959a-4d85-99b0-0c1d7ed131cd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_b57f08fd-de6d-4c87-8a34-1f4bcec19fa4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_fdd9f1c6-7c53-44a7-9f3f-08560667afc9" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_b57f08fd-de6d-4c87-8a34-1f4bcec19fa4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_b57f08fd-de6d-4c87-8a34-1f4bcec19fa4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_b57f08fd-de6d-4c87-8a34-1f4bcec19fa4" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_b57f08fd-de6d-4c87-8a34-1f4bcec19fa4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_73062cc1-73ef-4cc1-9bea-1b21b5d0d6fd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_b57f08fd-de6d-4c87-8a34-1f4bcec19fa4" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_73062cc1-73ef-4cc1-9bea-1b21b5d0d6fd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoRailMember_6abe55a9-0964-4711-a5a4-ed34681a44e9" xlink:href="hsc-20211231.xsd#hsc_HarscoRailMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_73062cc1-73ef-4cc1-9bea-1b21b5d0d6fd" xlink:to="loc_hsc_HarscoRailMember_6abe55a9-0964-4711-a5a4-ed34681a44e9" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/AcquisitionsandDispositionsSummaryofCashFlowInformationfromDisposalofHarscoRailSegmentDetails" xlink:type="simple" xlink:href="hsc-20211231.xsd#AcquisitionsandDispositionsSummaryofCashFlowInformationfromDisposalofHarscoRailSegmentDetails"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/AcquisitionsandDispositionsSummaryofCashFlowInformationfromDisposalofHarscoRailSegmentDetails" xlink:type="extended" id="i7e1a681b42a747fb9933dee0232c42a2_AcquisitionsandDispositionsSummaryofCashFlowInformationfromDisposalofHarscoRailSegmentDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_31a223a1-c9d7-40f4-873a-f4fc89a79d6b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationAndAmortizationDiscontinuedOperations_b8adb4ba-b2f9-450e-9d22-fae9baaf151d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DepreciationAndAmortizationDiscontinuedOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_31a223a1-c9d7-40f4-873a-f4fc89a79d6b" xlink:to="loc_us-gaap_DepreciationAndAmortizationDiscontinuedOperations_b8adb4ba-b2f9-450e-9d22-fae9baaf151d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalExpenditureDiscontinuedOperations_3590c0bf-c421-47ee-80fe-835bd8fb542d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CapitalExpenditureDiscontinuedOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_31a223a1-c9d7-40f4-873a-f4fc89a79d6b" xlink:to="loc_us-gaap_CapitalExpenditureDiscontinuedOperations_3590c0bf-c421-47ee-80fe-835bd8fb542d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_ba150fba-644a-4b71-a43f-efc17553088e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_31a223a1-c9d7-40f4-873a-f4fc89a79d6b" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_ba150fba-644a-4b71-a43f-efc17553088e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_5c9313de-1736-43d8-9fab-a8181f5ba26c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_ba150fba-644a-4b71-a43f-efc17553088e" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_5c9313de-1736-43d8-9fab-a8181f5ba26c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_5c9313de-1736-43d8-9fab-a8181f5ba26c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_5c9313de-1736-43d8-9fab-a8181f5ba26c" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_5c9313de-1736-43d8-9fab-a8181f5ba26c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_e0fb6bbc-b09c-47ab-949c-c78b72b7651f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_5c9313de-1736-43d8-9fab-a8181f5ba26c" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_e0fb6bbc-b09c-47ab-949c-c78b72b7651f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationsHeldforsaleMember_bd1dc41b-362b-4cde-850d-213a260d25fe" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DiscontinuedOperationsHeldforsaleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_e0fb6bbc-b09c-47ab-949c-c78b72b7651f" xlink:to="loc_us-gaap_DiscontinuedOperationsHeldforsaleMember_bd1dc41b-362b-4cde-850d-213a260d25fe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_96a69589-4940-42bf-8ff9-f0033f6e24ca" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_ba150fba-644a-4b71-a43f-efc17553088e" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_96a69589-4940-42bf-8ff9-f0033f6e24ca" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_96a69589-4940-42bf-8ff9-f0033f6e24ca_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_96a69589-4940-42bf-8ff9-f0033f6e24ca" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_96a69589-4940-42bf-8ff9-f0033f6e24ca_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_1ae2acbc-1698-4030-9b63-464077063c9d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_96a69589-4940-42bf-8ff9-f0033f6e24ca" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_1ae2acbc-1698-4030-9b63-464077063c9d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoRailMember_e6bbb91a-605a-4fa0-9fda-6e7b1215abae" xlink:href="hsc-20211231.xsd#hsc_HarscoRailMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_1ae2acbc-1698-4030-9b63-464077063c9d" xlink:to="loc_hsc_HarscoRailMember_e6bbb91a-605a-4fa0-9fda-6e7b1215abae" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/AcquisitionsandDispositionsNarrativeDetails" xlink:type="simple" xlink:href="hsc-20211231.xsd#AcquisitionsandDispositionsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/AcquisitionsandDispositionsNarrativeDetails" xlink:type="extended" id="iaf7a24c9fdf84def9b7268e15dc750c4_AcquisitionsandDispositionsNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_3a6f6fe3-3e0d-45f8-8f89-5cd6e8684d27" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DisposalGroupIncludingDiscontinuedOperationCorporateOverhead_4454f39c-5322-42b4-a61a-8846d1004dba" xlink:href="hsc-20211231.xsd#hsc_DisposalGroupIncludingDiscontinuedOperationCorporateOverhead"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3a6f6fe3-3e0d-45f8-8f89-5cd6e8684d27" xlink:to="loc_hsc_DisposalGroupIncludingDiscontinuedOperationCorporateOverhead_4454f39c-5322-42b4-a61a-8846d1004dba" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_fede058f-28be-419f-a6fe-76375cb9609d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3a6f6fe3-3e0d-45f8-8f89-5cd6e8684d27" xlink:to="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_fede058f-28be-419f-a6fe-76375cb9609d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_52d8d31c-0af8-4a64-835e-ae7a0fac81ce" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3a6f6fe3-3e0d-45f8-8f89-5cd6e8684d27" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_52d8d31c-0af8-4a64-835e-ae7a0fac81ce" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_BusinessCombinationAdditionalExpenseRelatedToReimbursementOfNOLFairValue_04750b0e-1901-4b29-ac5c-35692cecbcfd" xlink:href="hsc-20211231.xsd#hsc_BusinessCombinationAdditionalExpenseRelatedToReimbursementOfNOLFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3a6f6fe3-3e0d-45f8-8f89-5cd6e8684d27" xlink:to="loc_hsc_BusinessCombinationAdditionalExpenseRelatedToReimbursementOfNOLFairValue_04750b0e-1901-4b29-ac5c-35692cecbcfd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount_bfbf4fce-3cae-4c84-a576-3302a89fc221" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3a6f6fe3-3e0d-45f8-8f89-5cd6e8684d27" xlink:to="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount_bfbf4fce-3cae-4c84-a576-3302a89fc221" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_aa68e922-452f-4557-a4b6-348b2c7c821e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3a6f6fe3-3e0d-45f8-8f89-5cd6e8684d27" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_aa68e922-452f-4557-a4b6-348b2c7c821e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_4e46c020-0d87-4632-bccf-60717ef8a97c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3a6f6fe3-3e0d-45f8-8f89-5cd6e8684d27" xlink:to="loc_us-gaap_OperatingIncomeLoss_4e46c020-0d87-4632-bccf-60717ef8a97c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_01d67d74-e510-43f8-bb80-d4a7f2b3a166" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationAcquisitionRelatedCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3a6f6fe3-3e0d-45f8-8f89-5cd6e8684d27" xlink:to="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_01d67d74-e510-43f8-bb80-d4a7f2b3a166" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_a639fe04-c489-41de-8cc5-fa4685a0578b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3a6f6fe3-3e0d-45f8-8f89-5cd6e8684d27" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_a639fe04-c489-41de-8cc5-fa4685a0578b" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_BusinessCombinationContingentConsiderationArrangementsPostClosingPeriod_0bcb6b21-726b-4c75-89f3-62a02c560cd4" xlink:href="hsc-20211231.xsd#hsc_BusinessCombinationContingentConsiderationArrangementsPostClosingPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3a6f6fe3-3e0d-45f8-8f89-5cd6e8684d27" xlink:to="loc_hsc_BusinessCombinationContingentConsiderationArrangementsPostClosingPeriod_0bcb6b21-726b-4c75-89f3-62a02c560cd4" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_6702c87e-b2f9-42b8-80f3-5670ba4b48f9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3a6f6fe3-3e0d-45f8-8f89-5cd6e8684d27" xlink:to="loc_us-gaap_InterestExpense_6702c87e-b2f9-42b8-80f3-5670ba4b48f9" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_08f0c5aa-5c3a-48b2-923a-1bea8832a7a4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3a6f6fe3-3e0d-45f8-8f89-5cd6e8684d27" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_08f0c5aa-5c3a-48b2-923a-1bea8832a7a4" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration_b63ef0bc-6d6a-4083-9211-b72818ec0208" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3a6f6fe3-3e0d-45f8-8f89-5cd6e8684d27" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration_b63ef0bc-6d6a-4083-9211-b72818ec0208" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DisposalGroupNetGainonDisposalAfterTax_637fd083-1c0b-4555-ae9c-3e62bd4d6bed" xlink:href="hsc-20211231.xsd#hsc_DisposalGroupNetGainonDisposalAfterTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3a6f6fe3-3e0d-45f8-8f89-5cd6e8684d27" xlink:to="loc_hsc_DisposalGroupNetGainonDisposalAfterTax_637fd083-1c0b-4555-ae9c-3e62bd4d6bed" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DisposalGroupNetGainOnDisposalBeforeTax_58e5e2d5-caf8-4d74-a82d-e509e20744f2" xlink:href="hsc-20211231.xsd#hsc_DisposalGroupNetGainOnDisposalBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3a6f6fe3-3e0d-45f8-8f89-5cd6e8684d27" xlink:to="loc_hsc_DisposalGroupNetGainOnDisposalBeforeTax_58e5e2d5-caf8-4d74-a82d-e509e20744f2" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromDivestitureOfBusinesses_3a488cea-76b9-4b4f-abe9-fb158eb1e2e2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProceedsFromDivestitureOfBusinesses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3a6f6fe3-3e0d-45f8-8f89-5cd6e8684d27" xlink:to="loc_us-gaap_ProceedsFromDivestitureOfBusinesses_3a488cea-76b9-4b4f-abe9-fb158eb1e2e2" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableWithImputedInterestFaceAmount_6a55bb13-c471-48b2-980c-bfd56d1aba8e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ReceivableWithImputedInterestFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3a6f6fe3-3e0d-45f8-8f89-5cd6e8684d27" xlink:to="loc_us-gaap_ReceivableWithImputedInterestFaceAmount_6a55bb13-c471-48b2-980c-bfd56d1aba8e" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivablesFairValueDisclosure_7289368a-c761-4c69-bbff-a22151b9e25f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ReceivablesFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3a6f6fe3-3e0d-45f8-8f89-5cd6e8684d27" xlink:to="loc_us-gaap_ReceivablesFairValueDisclosure_7289368a-c761-4c69-bbff-a22151b9e25f" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationBeforeIncomeTax_2ad2f802-216a-4b8f-87a9-c8fef8af3639" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationBeforeIncomeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3a6f6fe3-3e0d-45f8-8f89-5cd6e8684d27" xlink:to="loc_us-gaap_DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationBeforeIncomeTax_2ad2f802-216a-4b8f-87a9-c8fef8af3639" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_7e023d7e-bf59-475e-b84b-0e685631035c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3a6f6fe3-3e0d-45f8-8f89-5cd6e8684d27" xlink:to="loc_us-gaap_Revenues_7e023d7e-bf59-475e-b84b-0e685631035c" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProvisionForLossOnContracts_76871cc7-03aa-4ed5-bf85-08491b7553d3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProvisionForLossOnContracts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3a6f6fe3-3e0d-45f8-8f89-5cd6e8684d27" xlink:to="loc_us-gaap_ProvisionForLossOnContracts_76871cc7-03aa-4ed5-bf85-08491b7553d3" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_PercentageComplete_106d528f-1833-4a60-8f8d-82ca8c39c3ff" xlink:href="hsc-20211231.xsd#hsc_PercentageComplete"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3a6f6fe3-3e0d-45f8-8f89-5cd6e8684d27" xlink:to="loc_hsc_PercentageComplete_106d528f-1833-4a60-8f8d-82ca8c39c3ff" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_021e6e74-27f2-4d3a-a2f6-49f2f6c7f65d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3a6f6fe3-3e0d-45f8-8f89-5cd6e8684d27" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_021e6e74-27f2-4d3a-a2f6-49f2f6c7f65d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonrecurringAdjustmentAxis_3aa1a055-7f30-486f-9ec7-2eecefe72351" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NonrecurringAdjustmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_021e6e74-27f2-4d3a-a2f6-49f2f6c7f65d" xlink:to="loc_us-gaap_NonrecurringAdjustmentAxis_3aa1a055-7f30-486f-9ec7-2eecefe72351" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonrecurringAdjustmentDomain_3aa1a055-7f30-486f-9ec7-2eecefe72351_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NonrecurringAdjustmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_NonrecurringAdjustmentAxis_3aa1a055-7f30-486f-9ec7-2eecefe72351" xlink:to="loc_us-gaap_NonrecurringAdjustmentDomain_3aa1a055-7f30-486f-9ec7-2eecefe72351_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonrecurringAdjustmentDomain_3967d947-617b-4ee2-8eab-932018feb4dc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NonrecurringAdjustmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_NonrecurringAdjustmentAxis_3aa1a055-7f30-486f-9ec7-2eecefe72351" xlink:to="loc_us-gaap_NonrecurringAdjustmentDomain_3967d947-617b-4ee2-8eab-932018feb4dc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_cae0274f-868b-4a16-b331-49998c624a05" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_021e6e74-27f2-4d3a-a2f6-49f2f6c7f65d" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_cae0274f-868b-4a16-b331-49998c624a05" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_cae0274f-868b-4a16-b331-49998c624a05_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_cae0274f-868b-4a16-b331-49998c624a05" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_cae0274f-868b-4a16-b331-49998c624a05_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_0602acb9-1472-4c79-86e2-576e1f98585a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_cae0274f-868b-4a16-b331-49998c624a05" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_0602acb9-1472-4c79-86e2-576e1f98585a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoIndustrialMember_81c9be4d-97bd-4b02-83b9-ab0fa163b809" xlink:href="hsc-20211231.xsd#hsc_HarscoIndustrialMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_0602acb9-1472-4c79-86e2-576e1f98585a" xlink:to="loc_hsc_HarscoIndustrialMember_81c9be4d-97bd-4b02-83b9-ab0fa163b809" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoIndustrialPattersonKelleyMember_135e9bf5-cdbb-4f72-842b-104a3b1821d2" xlink:href="hsc-20211231.xsd#hsc_HarscoIndustrialPattersonKelleyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_0602acb9-1472-4c79-86e2-576e1f98585a" xlink:to="loc_hsc_HarscoIndustrialPattersonKelleyMember_135e9bf5-cdbb-4f72-842b-104a3b1821d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoIndustrialIKGMember_2c0b20e1-b665-4073-9065-9b7a6c12d8a6" xlink:href="hsc-20211231.xsd#hsc_HarscoIndustrialIKGMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_0602acb9-1472-4c79-86e2-576e1f98585a" xlink:to="loc_hsc_HarscoIndustrialIKGMember_2c0b20e1-b665-4073-9065-9b7a6c12d8a6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoIndustrialAirXChangersBusinessMember_17e2f14f-f3dd-441a-9661-eb745dfef49d" xlink:href="hsc-20211231.xsd#hsc_HarscoIndustrialAirXChangersBusinessMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_0602acb9-1472-4c79-86e2-576e1f98585a" xlink:to="loc_hsc_HarscoIndustrialAirXChangersBusinessMember_17e2f14f-f3dd-441a-9661-eb745dfef49d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoRailMember_c8743905-c32e-4053-bdac-13f6315f338d" xlink:href="hsc-20211231.xsd#hsc_HarscoRailMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_0602acb9-1472-4c79-86e2-576e1f98585a" xlink:to="loc_hsc_HarscoRailMember_c8743905-c32e-4053-bdac-13f6315f338d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_655e88da-3075-45cb-b48c-ee9e58b738cf" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_021e6e74-27f2-4d3a-a2f6-49f2f6c7f65d" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_655e88da-3075-45cb-b48c-ee9e58b738cf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_655e88da-3075-45cb-b48c-ee9e58b738cf_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_655e88da-3075-45cb-b48c-ee9e58b738cf" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_655e88da-3075-45cb-b48c-ee9e58b738cf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_b77a1339-8832-45c6-8b8d-8562187c5d11" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_655e88da-3075-45cb-b48c-ee9e58b738cf" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_b77a1339-8832-45c6-8b8d-8562187c5d11" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationsHeldforsaleMember_8244c3fd-319e-4631-aa05-bae98303fcbc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DiscontinuedOperationsHeldforsaleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_b77a1339-8832-45c6-8b8d-8562187c5d11" xlink:to="loc_us-gaap_DiscontinuedOperationsHeldforsaleMember_8244c3fd-319e-4631-aa05-bae98303fcbc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_3eb94ef1-ed24-46e9-94d1-78b0d1a56544" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_b77a1339-8832-45c6-8b8d-8562187c5d11" xlink:to="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_3eb94ef1-ed24-46e9-94d1-78b0d1a56544" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_fe7662dc-16ab-42e7-b236-91b5c9428783" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_021e6e74-27f2-4d3a-a2f6-49f2f6c7f65d" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_fe7662dc-16ab-42e7-b236-91b5c9428783" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_fe7662dc-16ab-42e7-b236-91b5c9428783_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_fe7662dc-16ab-42e7-b236-91b5c9428783" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_fe7662dc-16ab-42e7-b236-91b5c9428783_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_c951c767-4c29-4c56-bda0-0cb1cee97b28" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_fe7662dc-16ab-42e7-b236-91b5c9428783" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_c951c767-4c29-4c56-bda0-0cb1cee97b28" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_CleanEarthMember_24888c08-1616-4a8f-8160-db5c4a0814aa" xlink:href="hsc-20211231.xsd#hsc_CleanEarthMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_c951c767-4c29-4c56-bda0-0cb1cee97b28" xlink:to="loc_hsc_CleanEarthMember_24888c08-1616-4a8f-8160-db5c4a0814aa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ESOLMember_d48df949-b748-496b-8f5a-e4a5fd9b3084" xlink:href="hsc-20211231.xsd#hsc_ESOLMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_c951c767-4c29-4c56-bda0-0cb1cee97b28" xlink:to="loc_hsc_ESOLMember_d48df949-b748-496b-8f5a-e4a5fd9b3084" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_bffc5160-881c-46c5-acf1-df6badcfb4ce" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_021e6e74-27f2-4d3a-a2f6-49f2f6c7f65d" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_bffc5160-881c-46c5-acf1-df6badcfb4ce" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_bffc5160-881c-46c5-acf1-df6badcfb4ce_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_bffc5160-881c-46c5-acf1-df6badcfb4ce" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_bffc5160-881c-46c5-acf1-df6badcfb4ce_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_ce531653-7752-4779-9d9d-5f3975577e2e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_bffc5160-881c-46c5-acf1-df6badcfb4ce" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_ce531653-7752-4779-9d9d-5f3975577e2e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_0c7fd4a5-dd30-4a4b-ab42-cdaea9251805" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_021e6e74-27f2-4d3a-a2f6-49f2f6c7f65d" xlink:to="loc_srt_MajorCustomersAxis_0c7fd4a5-dd30-4a4b-ab42-cdaea9251805" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_0c7fd4a5-dd30-4a4b-ab42-cdaea9251805_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_0c7fd4a5-dd30-4a4b-ab42-cdaea9251805" xlink:to="loc_srt_NameOfMajorCustomerDomain_0c7fd4a5-dd30-4a4b-ab42-cdaea9251805_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_a10782a5-8f4a-44e5-8ef7-d2c63af6bfdd" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_0c7fd4a5-dd30-4a4b-ab42-cdaea9251805" xlink:to="loc_srt_NameOfMajorCustomerDomain_a10782a5-8f4a-44e5-8ef7-d2c63af6bfdd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_SBBMember_92061ca8-4107-48d8-8848-7f16bc2ab9d8" xlink:href="hsc-20211231.xsd#hsc_SBBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_a10782a5-8f4a-44e5-8ef7-d2c63af6bfdd" xlink:to="loc_hsc_SBBMember_92061ca8-4107-48d8-8848-7f16bc2ab9d8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_NetworkRailMember_943d5600-1dff-4d22-9e15-27cf7d1126e5" xlink:href="hsc-20211231.xsd#hsc_NetworkRailMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_a10782a5-8f4a-44e5-8ef7-d2c63af6bfdd" xlink:to="loc_hsc_NetworkRailMember_943d5600-1dff-4d22-9e15-27cf7d1126e5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DeutscheBahnMember_f54bdf70-7ff6-4d28-b17b-4b57299554cf" xlink:href="hsc-20211231.xsd#hsc_DeutscheBahnMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_a10782a5-8f4a-44e5-8ef7-d2c63af6bfdd" xlink:to="loc_hsc_DeutscheBahnMember_f54bdf70-7ff6-4d28-b17b-4b57299554cf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ContractAxis_4c941409-7800-4c37-bf5b-941dc7269771" xlink:href="hsc-20211231.xsd#hsc_ContractAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_021e6e74-27f2-4d3a-a2f6-49f2f6c7f65d" xlink:to="loc_hsc_ContractAxis_4c941409-7800-4c37-bf5b-941dc7269771" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ContractDomain_4c941409-7800-4c37-bf5b-941dc7269771_default" xlink:href="hsc-20211231.xsd#hsc_ContractDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_hsc_ContractAxis_4c941409-7800-4c37-bf5b-941dc7269771" xlink:to="loc_hsc_ContractDomain_4c941409-7800-4c37-bf5b-941dc7269771_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ContractDomain_e5b6f2aa-e3ca-48d4-9c41-36d5dc6dc064" xlink:href="hsc-20211231.xsd#hsc_ContractDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_hsc_ContractAxis_4c941409-7800-4c37-bf5b-941dc7269771" xlink:to="loc_hsc_ContractDomain_e5b6f2aa-e3ca-48d4-9c41-36d5dc6dc064" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_Contract2Member_dff34054-f724-4fd5-990b-471aadb0cb10" xlink:href="hsc-20211231.xsd#hsc_Contract2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hsc_ContractDomain_e5b6f2aa-e3ca-48d4-9c41-36d5dc6dc064" xlink:to="loc_hsc_Contract2Member_dff34054-f724-4fd5-990b-471aadb0cb10" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/AcquisitionsandDispositionsSummaryofAssetsAcquiredandLiabilitiesAssumedDetails" xlink:type="simple" xlink:href="hsc-20211231.xsd#AcquisitionsandDispositionsSummaryofAssetsAcquiredandLiabilitiesAssumedDetails"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/AcquisitionsandDispositionsSummaryofAssetsAcquiredandLiabilitiesAssumedDetails" xlink:type="extended" id="ia85f7434b3044cdbaa129868689247b6_AcquisitionsandDispositionsSummaryofAssetsAcquiredandLiabilitiesAssumedDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_00822fb7-0a2c-43b1-a312-3349f6d70e74" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_5bd35616-a5f5-47ce-9061-3babb0967534" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_00822fb7-0a2c-43b1-a312-3349f6d70e74" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_5bd35616-a5f5-47ce-9061-3babb0967534" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_99f259c4-f276-4a84-84da-75ece7c0cdb9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_5bd35616-a5f5-47ce-9061-3babb0967534" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_99f259c4-f276-4a84-84da-75ece7c0cdb9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsTradeReceivables_2de999da-43ae-45ea-878b-5bca93a5a225" xlink:href="hsc-20211231.xsd#hsc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsTradeReceivables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_5bd35616-a5f5-47ce-9061-3babb0967534" xlink:to="loc_hsc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsTradeReceivables_2de999da-43ae-45ea-878b-5bca93a5a225" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory_c21bccab-a3d9-4364-acd7-13990a50159a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_5bd35616-a5f5-47ce-9061-3babb0967534" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory_c21bccab-a3d9-4364-acd7-13990a50159a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsOther_21706e53-7f1f-4e04-b710-28514f016f7f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_5bd35616-a5f5-47ce-9061-3babb0967534" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsOther_21706e53-7f1f-4e04-b710-28514f016f7f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_6a24ecd1-a1d5-4a6a-9ad3-11e2850c4f36" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_5bd35616-a5f5-47ce-9061-3babb0967534" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_6a24ecd1-a1d5-4a6a-9ad3-11e2850c4f36" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseRightofUseAsset_d255c806-2123-4f65-9ffb-a9ba7552bcb3" xlink:href="hsc-20211231.xsd#hsc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseRightofUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_5bd35616-a5f5-47ce-9061-3babb0967534" xlink:to="loc_hsc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseRightofUseAsset_d255c806-2123-4f65-9ffb-a9ba7552bcb3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_7881d583-c426-4085-b110-36f8cc7e6fed" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_5bd35616-a5f5-47ce-9061-3babb0967534" xlink:to="loc_us-gaap_Goodwill_7881d583-c426-4085-b110-36f8cc7e6fed" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_76871f98-da05-4786-9436-a226a065fde4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_5bd35616-a5f5-47ce-9061-3babb0967534" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_76871f98-da05-4786-9436-a226a065fde4" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_2dd7706b-fa89-487f-9964-acb792e19afd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_5bd35616-a5f5-47ce-9061-3babb0967534" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_2dd7706b-fa89-487f-9964-acb792e19afd" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_04009093-0879-4cfe-a5d1-b46436fb4233" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_5bd35616-a5f5-47ce-9061-3babb0967534" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_04009093-0879-4cfe-a5d1-b46436fb4233" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAccruedExpenses_aad285c9-3377-4712-b661-e807cb3c3851" xlink:href="hsc-20211231.xsd#hsc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAccruedExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_5bd35616-a5f5-47ce-9061-3babb0967534" xlink:to="loc_hsc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAccruedExpenses_aad285c9-3377-4712-b661-e807cb3c3851" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrent_87c84345-aa50-45b6-a15a-a747b37afc22" xlink:href="hsc-20211231.xsd#hsc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_5bd35616-a5f5-47ce-9061-3babb0967534" xlink:to="loc_hsc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrent_87c84345-aa50-45b6-a15a-a747b37afc22" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesOther_39d96c26-4f21-4608-8b08-312648c3a562" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_5bd35616-a5f5-47ce-9061-3babb0967534" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesOther_39d96c26-4f21-4608-8b08-312648c3a562" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedEnvironmental_ebe5ef84-3c70-485d-b762-db9b81702f8b" xlink:href="hsc-20211231.xsd#hsc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedEnvironmental"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_5bd35616-a5f5-47ce-9061-3babb0967534" xlink:to="loc_hsc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedEnvironmental_ebe5ef84-3c70-485d-b762-db9b81702f8b" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_ced30b80-c0d9-4604-bda2-ea493f94bff1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_5bd35616-a5f5-47ce-9061-3babb0967534" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_ced30b80-c0d9-4604-bda2-ea493f94bff1" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCapitalLeaseObligation_e6dbc6b2-dbb7-4099-9af4-dcc6ef4cfcca" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCapitalLeaseObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_5bd35616-a5f5-47ce-9061-3babb0967534" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCapitalLeaseObligation_e6dbc6b2-dbb7-4099-9af4-dcc6ef4cfcca" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_1fa29be8-ba52-4467-bcc8-bec4e18b7d45" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_5bd35616-a5f5-47ce-9061-3babb0967534" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_1fa29be8-ba52-4467-bcc8-bec4e18b7d45" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsOtherReceivables_0445f74c-4e8c-4053-8670-2d7a9b030ddc" xlink:href="hsc-20211231.xsd#hsc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsOtherReceivables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_5bd35616-a5f5-47ce-9061-3babb0967534" xlink:to="loc_hsc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsOtherReceivables_0445f74c-4e8c-4053-8670-2d7a9b030ddc" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAcquisitionConsiderationPayable_54df57b2-b78f-480d-9eda-9f76588e720f" xlink:href="hsc-20211231.xsd#hsc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAcquisitionConsiderationPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_5bd35616-a5f5-47ce-9061-3babb0967534" xlink:to="loc_hsc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAcquisitionConsiderationPayable_54df57b2-b78f-480d-9eda-9f76588e720f" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_de434f60-2a1d-4f77-be65-c8c80d08410b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_5bd35616-a5f5-47ce-9061-3babb0967534" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_de434f60-2a1d-4f77-be65-c8c80d08410b" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_d3f3b6b7-e9f8-4ba5-b9ed-0549c08cdaab" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_5bd35616-a5f5-47ce-9061-3babb0967534" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_d3f3b6b7-e9f8-4ba5-b9ed-0549c08cdaab" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_BusinessAcquisitionsPurchasePriceAllocation_0f441164-3235-49c8-b5e8-eacb07de28b4" xlink:href="hsc-20211231.xsd#hsc_BusinessAcquisitionsPurchasePriceAllocation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_5bd35616-a5f5-47ce-9061-3babb0967534" xlink:to="loc_hsc_BusinessAcquisitionsPurchasePriceAllocation_0f441164-3235-49c8-b5e8-eacb07de28b4" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_2d8e7bbf-0809-4109-a18a-427855bc610f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_00822fb7-0a2c-43b1-a312-3349f6d70e74" xlink:to="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_2d8e7bbf-0809-4109-a18a-427855bc610f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentCash_4168fd50-c57b-4bcc-ae63-4e10d6db717c" xlink:href="hsc-20211231.xsd#hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_2d8e7bbf-0809-4109-a18a-427855bc610f" xlink:to="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentCash_4168fd50-c57b-4bcc-ae63-4e10d6db717c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustment_2049c5f2-a438-4556-8219-c54b6bd25751" xlink:href="hsc-20211231.xsd#hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_2d8e7bbf-0809-4109-a18a-427855bc610f" xlink:to="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustment_2049c5f2-a438-4556-8219-c54b6bd25751" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherReceivables_d54ddd58-3359-43db-a2de-19c94f25c2f0" xlink:href="hsc-20211231.xsd#hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherReceivables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_2d8e7bbf-0809-4109-a18a-427855bc610f" xlink:to="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherReceivables_d54ddd58-3359-43db-a2de-19c94f25c2f0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentEnvironmentalLiabilities_e95be02f-fe8f-4912-9731-77dc624ec7ae" xlink:href="hsc-20211231.xsd#hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentEnvironmentalLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_2d8e7bbf-0809-4109-a18a-427855bc610f" xlink:to="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentEnvironmentalLiabilities_e95be02f-fe8f-4912-9731-77dc624ec7ae" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherCurrentAssets_fc7eae3e-c6c4-4355-8f7d-c5ee8b023536" xlink:href="hsc-20211231.xsd#hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherCurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_2d8e7bbf-0809-4109-a18a-427855bc610f" xlink:to="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherCurrentAssets_fc7eae3e-c6c4-4355-8f7d-c5ee8b023536" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentPurchasePriceAllocation_f4f04b01-563b-42bd-aed9-21d4035b9c28" xlink:href="hsc-20211231.xsd#hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentPurchasePriceAllocation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_2d8e7bbf-0809-4109-a18a-427855bc610f" xlink:to="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentPurchasePriceAllocation_f4f04b01-563b-42bd-aed9-21d4035b9c28" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentCurrentPortionOfOperatingLeaseLiabilities_f7801252-94f3-487d-95f7-86139d392c95" xlink:href="hsc-20211231.xsd#hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentCurrentPortionOfOperatingLeaseLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_2d8e7bbf-0809-4109-a18a-427855bc610f" xlink:to="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentCurrentPortionOfOperatingLeaseLiabilities_f7801252-94f3-487d-95f7-86139d392c95" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentPropertyPlantAndEquipment_822e351c-c9ba-42e1-a5e7-4a83b94bcff2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_2d8e7bbf-0809-4109-a18a-427855bc610f" xlink:to="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentPropertyPlantAndEquipment_822e351c-c9ba-42e1-a5e7-4a83b94bcff2" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentRightofUseAsset_63e59054-ed02-4e2d-92bc-26243b267a41" xlink:href="hsc-20211231.xsd#hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentRightofUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_2d8e7bbf-0809-4109-a18a-427855bc610f" xlink:to="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentRightofUseAsset_63e59054-ed02-4e2d-92bc-26243b267a41" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentInventory_eb0cda7e-6d4e-430a-b19b-9c61b3daf922" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentInventory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_2d8e7bbf-0809-4109-a18a-427855bc610f" xlink:to="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentInventory_eb0cda7e-6d4e-430a-b19b-9c61b3daf922" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherAssets_c74916ae-13e0-4041-bdbb-92135b3b9caf" xlink:href="hsc-20211231.xsd#hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_2d8e7bbf-0809-4109-a18a-427855bc610f" xlink:to="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherAssets_c74916ae-13e0-4041-bdbb-92135b3b9caf" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAcquisitionConsiderationPayable_10dfefd1-645e-4720-ad88-77281fb46574" xlink:href="hsc-20211231.xsd#hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAcquisitionConsiderationPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_2d8e7bbf-0809-4109-a18a-427855bc610f" xlink:to="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAcquisitionConsiderationPayable_10dfefd1-645e-4720-ad88-77281fb46574" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherCurrentLiabilities_1f8043b3-79bc-48b7-9a37-295d43c427ca" xlink:href="hsc-20211231.xsd#hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherCurrentLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_2d8e7bbf-0809-4109-a18a-427855bc610f" xlink:to="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherCurrentLiabilities_1f8043b3-79bc-48b7-9a37-295d43c427ca" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccruedExpenses_040c8a07-e7c3-4509-93ad-b60f8b2cd356" xlink:href="hsc-20211231.xsd#hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccruedExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_2d8e7bbf-0809-4109-a18a-427855bc610f" xlink:to="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccruedExpenses_040c8a07-e7c3-4509-93ad-b60f8b2cd356" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccountsPayable_171e3bae-cacc-434d-b1ba-653682bc206f" xlink:href="hsc-20211231.xsd#hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccountsPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_2d8e7bbf-0809-4109-a18a-427855bc610f" xlink:to="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccountsPayable_171e3bae-cacc-434d-b1ba-653682bc206f" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentNetdeferredTaxesLiability_b750a6f0-1921-4b8b-b8dc-fea0f0eba472" xlink:href="hsc-20211231.xsd#hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentNetdeferredTaxesLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_2d8e7bbf-0809-4109-a18a-427855bc610f" xlink:to="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentNetdeferredTaxesLiability_b750a6f0-1921-4b8b-b8dc-fea0f0eba472" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOperatingleaseliabilities_6396808e-44d5-44c6-af46-63080af02e8b" xlink:href="hsc-20211231.xsd#hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOperatingleaseliabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_2d8e7bbf-0809-4109-a18a-427855bc610f" xlink:to="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOperatingleaseliabilities_6396808e-44d5-44c6-af46-63080af02e8b" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherLiabilities_57cc62bd-1def-4320-84d3-31d8947632cc" xlink:href="hsc-20211231.xsd#hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_2d8e7bbf-0809-4109-a18a-427855bc610f" xlink:to="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherLiabilities_57cc62bd-1def-4320-84d3-31d8947632cc" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentIntangibles_b2895708-b530-451c-b4b7-adf2a575f7e6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentIntangibles"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_2d8e7bbf-0809-4109-a18a-427855bc610f" xlink:to="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentIntangibles_b2895708-b530-451c-b4b7-adf2a575f7e6" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentGoodwill_a57e9d0a-19dc-4dd9-9384-4cc39011b6d6" xlink:href="hsc-20211231.xsd#hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_2d8e7bbf-0809-4109-a18a-427855bc610f" xlink:to="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentGoodwill_a57e9d0a-19dc-4dd9-9384-4cc39011b6d6" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentConsiderationTransferred_525ccf80-0c0b-4466-945f-87f6f7a70abc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentConsiderationTransferred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsAbstract_2d8e7bbf-0809-4109-a18a-427855bc610f" xlink:to="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentConsiderationTransferred_525ccf80-0c0b-4466-945f-87f6f7a70abc" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8e207d07-07ae-4daa-84d9-f3c28342beba" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_00822fb7-0a2c-43b1-a312-3349f6d70e74" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8e207d07-07ae-4daa-84d9-f3c28342beba" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_def08283-dc91-4e3c-b28f-587d9d73cff2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8e207d07-07ae-4daa-84d9-f3c28342beba" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_def08283-dc91-4e3c-b28f-587d9d73cff2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_def08283-dc91-4e3c-b28f-587d9d73cff2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_def08283-dc91-4e3c-b28f-587d9d73cff2" xlink:to="loc_us-gaap_SegmentDomain_def08283-dc91-4e3c-b28f-587d9d73cff2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_4055a57a-53d7-42d0-87fe-197ad8f95f21" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_def08283-dc91-4e3c-b28f-587d9d73cff2" xlink:to="loc_us-gaap_SegmentDomain_4055a57a-53d7-42d0-87fe-197ad8f95f21" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_CleanEarthMember_694cab07-a47b-47f2-b50d-e3bfd693684a" xlink:href="hsc-20211231.xsd#hsc_CleanEarthMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_4055a57a-53d7-42d0-87fe-197ad8f95f21" xlink:to="loc_hsc_CleanEarthMember_694cab07-a47b-47f2-b50d-e3bfd693684a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_d0c160af-2aa2-4f17-a2e9-1328b883fe17" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8e207d07-07ae-4daa-84d9-f3c28342beba" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_d0c160af-2aa2-4f17-a2e9-1328b883fe17" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_d0c160af-2aa2-4f17-a2e9-1328b883fe17_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_d0c160af-2aa2-4f17-a2e9-1328b883fe17" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_d0c160af-2aa2-4f17-a2e9-1328b883fe17_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_a2416552-3e5b-479e-8eb5-fde524405071" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_d0c160af-2aa2-4f17-a2e9-1328b883fe17" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_a2416552-3e5b-479e-8eb5-fde524405071" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoIndustrialMember_0d16a242-d3c7-4f55-84a8-a33683209ff4" xlink:href="hsc-20211231.xsd#hsc_HarscoIndustrialMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_a2416552-3e5b-479e-8eb5-fde524405071" xlink:to="loc_hsc_HarscoIndustrialMember_0d16a242-d3c7-4f55-84a8-a33683209ff4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_1f77a2bf-54f7-4dce-b6e5-331b231e804b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8e207d07-07ae-4daa-84d9-f3c28342beba" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_1f77a2bf-54f7-4dce-b6e5-331b231e804b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_1f77a2bf-54f7-4dce-b6e5-331b231e804b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_1f77a2bf-54f7-4dce-b6e5-331b231e804b" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_1f77a2bf-54f7-4dce-b6e5-331b231e804b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_f7beda38-c15e-42f6-978f-57eafac0d335" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_1f77a2bf-54f7-4dce-b6e5-331b231e804b" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_f7beda38-c15e-42f6-978f-57eafac0d335" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationsHeldforsaleMember_7884ad57-37b9-448d-a592-ff83f5f35f13" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DiscontinuedOperationsHeldforsaleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_f7beda38-c15e-42f6-978f-57eafac0d335" xlink:to="loc_us-gaap_DiscontinuedOperationsHeldforsaleMember_7884ad57-37b9-448d-a592-ff83f5f35f13" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_23922cfc-bbaf-4e68-910c-e03e166f6c99" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8e207d07-07ae-4daa-84d9-f3c28342beba" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_23922cfc-bbaf-4e68-910c-e03e166f6c99" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_23922cfc-bbaf-4e68-910c-e03e166f6c99_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_23922cfc-bbaf-4e68-910c-e03e166f6c99" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_23922cfc-bbaf-4e68-910c-e03e166f6c99_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8464e127-32be-44aa-80b7-bcefe92f90e5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_23922cfc-bbaf-4e68-910c-e03e166f6c99" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8464e127-32be-44aa-80b7-bcefe92f90e5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_CleanEarthMember_47630e22-93d8-4b05-a798-4e2316889882" xlink:href="hsc-20211231.xsd#hsc_CleanEarthMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8464e127-32be-44aa-80b7-bcefe92f90e5" xlink:to="loc_hsc_CleanEarthMember_47630e22-93d8-4b05-a798-4e2316889882" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ESOLMember_cc11a72d-2593-46ab-bf01-da2be62c52d5" xlink:href="hsc-20211231.xsd#hsc_ESOLMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8464e127-32be-44aa-80b7-bcefe92f90e5" xlink:to="loc_hsc_ESOLMember_cc11a72d-2593-46ab-bf01-da2be62c52d5" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/AcquisitionsandDispositionsSummaryofIntangibleAssetsandAmortizationPeriodsDetails" xlink:type="simple" xlink:href="hsc-20211231.xsd#AcquisitionsandDispositionsSummaryofIntangibleAssetsandAmortizationPeriodsDetails"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/AcquisitionsandDispositionsSummaryofIntangibleAssetsandAmortizationPeriodsDetails" xlink:type="extended" id="i027486497b91434d9d605dcb7c4053bc_AcquisitionsandDispositionsSummaryofIntangibleAssetsandAmortizationPeriodsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_7c0f63ef-5787-4aa9-8181-d544824467a5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_9feb6686-cfca-43d0-9cb8-5724391f5617" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_7c0f63ef-5787-4aa9-8181-d544824467a5" xlink:to="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_9feb6686-cfca-43d0-9cb8-5724391f5617" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_cd38873b-997b-44ef-a4d1-6991e81d56d5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_7c0f63ef-5787-4aa9-8181-d544824467a5" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_cd38873b-997b-44ef-a4d1-6991e81d56d5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentPermits_447804e8-4d7a-40fd-9f97-85a06b9208aa" xlink:href="hsc-20211231.xsd#hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentPermits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_7c0f63ef-5787-4aa9-8181-d544824467a5" xlink:to="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentPermits_447804e8-4d7a-40fd-9f97-85a06b9208aa" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentCustomerRelationships_aea353fb-084a-488b-95a5-e4fdc3d8564b" xlink:href="hsc-20211231.xsd#hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentCustomerRelationships"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_7c0f63ef-5787-4aa9-8181-d544824467a5" xlink:to="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentCustomerRelationships_aea353fb-084a-488b-95a5-e4fdc3d8564b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentIntangibles_d389e867-231c-427d-b175-163a3824f1ac" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentIntangibles"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_7c0f63ef-5787-4aa9-8181-d544824467a5" xlink:to="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentIntangibles_d389e867-231c-427d-b175-163a3824f1ac" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_110f210d-15ca-4235-9bb8-528a65ac4674" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_7c0f63ef-5787-4aa9-8181-d544824467a5" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_110f210d-15ca-4235-9bb8-528a65ac4674" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_BusinessCombinationRecognizedIdentifiableIntangibleAssetsAcquiredAndLiabilitiesAssumedFiniteLivedIntangiblesIncludingNonCompete_3c0b0aef-f049-4e55-a8d8-cd1cabce63cb" xlink:href="hsc-20211231.xsd#hsc_BusinessCombinationRecognizedIdentifiableIntangibleAssetsAcquiredAndLiabilitiesAssumedFiniteLivedIntangiblesIncludingNonCompete"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_7c0f63ef-5787-4aa9-8181-d544824467a5" xlink:to="loc_hsc_BusinessCombinationRecognizedIdentifiableIntangibleAssetsAcquiredAndLiabilitiesAssumedFiniteLivedIntangiblesIncludingNonCompete_3c0b0aef-f049-4e55-a8d8-cd1cabce63cb" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsIntangiblesIncludingNonCompete_7cff86f8-128a-4048-b41f-6f1150ad1b4f" xlink:href="hsc-20211231.xsd#hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsIntangiblesIncludingNonCompete"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_7c0f63ef-5787-4aa9-8181-d544824467a5" xlink:to="loc_hsc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentsIntangiblesIncludingNonCompete_7cff86f8-128a-4048-b41f-6f1150ad1b4f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAcquiredAsPartOfBusinessCombinationTable_69848b6c-44fb-441e-9780-c66697be5d0f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAcquiredAsPartOfBusinessCombinationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_7c0f63ef-5787-4aa9-8181-d544824467a5" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAcquiredAsPartOfBusinessCombinationTable_69848b6c-44fb-441e-9780-c66697be5d0f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_ba62adac-142b-4bfe-8f3f-d053fff7a3d7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsAcquiredAsPartOfBusinessCombinationTable_69848b6c-44fb-441e-9780-c66697be5d0f" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_ba62adac-142b-4bfe-8f3f-d053fff7a3d7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ba62adac-142b-4bfe-8f3f-d053fff7a3d7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_ba62adac-142b-4bfe-8f3f-d053fff7a3d7" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ba62adac-142b-4bfe-8f3f-d053fff7a3d7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_fbfdecaa-a245-411f-894c-2f88bcc6d256" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_ba62adac-142b-4bfe-8f3f-d053fff7a3d7" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_fbfdecaa-a245-411f-894c-2f88bcc6d256" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_CleanEarthMember_6f5a305d-69c4-42ca-90c8-19167bb06e6a" xlink:href="hsc-20211231.xsd#hsc_CleanEarthMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_fbfdecaa-a245-411f-894c-2f88bcc6d256" xlink:to="loc_hsc_CleanEarthMember_6f5a305d-69c4-42ca-90c8-19167bb06e6a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ESOLMember_7f4c076f-8313-4ce6-bde7-a0b9bc3f77b3" xlink:href="hsc-20211231.xsd#hsc_ESOLMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_fbfdecaa-a245-411f-894c-2f88bcc6d256" xlink:to="loc_hsc_ESOLMember_7f4c076f-8313-4ce6-bde7-a0b9bc3f77b3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_fd87069a-3931-4d0c-8949-f00c594da4fa" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsAcquiredAsPartOfBusinessCombinationTable_69848b6c-44fb-441e-9780-c66697be5d0f" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_fd87069a-3931-4d0c-8949-f00c594da4fa" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_fd87069a-3931-4d0c-8949-f00c594da4fa_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_fd87069a-3931-4d0c-8949-f00c594da4fa" xlink:to="loc_us-gaap_SegmentDomain_fd87069a-3931-4d0c-8949-f00c594da4fa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_b792873e-3add-451e-9522-13483c0825af" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_fd87069a-3931-4d0c-8949-f00c594da4fa" xlink:to="loc_us-gaap_SegmentDomain_b792873e-3add-451e-9522-13483c0825af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_CleanEarthMember_bcf3d157-e381-44bb-897d-63d67c33761c" xlink:href="hsc-20211231.xsd#hsc_CleanEarthMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_b792873e-3add-451e-9522-13483c0825af" xlink:to="loc_hsc_CleanEarthMember_bcf3d157-e381-44bb-897d-63d67c33761c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_9e7dde0e-131a-49d7-8474-b3632c1dfaf7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsAcquiredAsPartOfBusinessCombinationTable_69848b6c-44fb-441e-9780-c66697be5d0f" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_9e7dde0e-131a-49d7-8474-b3632c1dfaf7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_9e7dde0e-131a-49d7-8474-b3632c1dfaf7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_9e7dde0e-131a-49d7-8474-b3632c1dfaf7" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_9e7dde0e-131a-49d7-8474-b3632c1dfaf7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_86e45163-61e9-42a6-b34c-4f27d229991a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_9e7dde0e-131a-49d7-8474-b3632c1dfaf7" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_86e45163-61e9-42a6-b34c-4f27d229991a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_PermitsAndRightsMember_8b18b739-a714-4025-9cb9-0a20dc65b70a" xlink:href="hsc-20211231.xsd#hsc_PermitsAndRightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_86e45163-61e9-42a6-b34c-4f27d229991a" xlink:to="loc_hsc_PermitsAndRightsMember_8b18b739-a714-4025-9cb9-0a20dc65b70a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_bece419f-4b50-432c-8152-51cf220cdd3a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_86e45163-61e9-42a6-b34c-4f27d229991a" xlink:to="loc_us-gaap_CustomerRelationshipsMember_bece419f-4b50-432c-8152-51cf220cdd3a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_AirRightsMember_b6410ceb-e7eb-4a72-ae08-24a599bd5005" xlink:href="hsc-20211231.xsd#hsc_AirRightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_86e45163-61e9-42a6-b34c-4f27d229991a" xlink:to="loc_hsc_AirRightsMember_b6410ceb-e7eb-4a72-ae08-24a599bd5005" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TradeNamesMember_4c335eec-5fb4-4812-8e89-f92b58de2dac" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_86e45163-61e9-42a6-b34c-4f27d229991a" xlink:to="loc_us-gaap_TradeNamesMember_4c335eec-5fb4-4812-8e89-f92b58de2dac" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncompeteAgreementsMember_71e6b1b5-9e71-44cb-ae04-89be13df88c9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NoncompeteAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_86e45163-61e9-42a6-b34c-4f27d229991a" xlink:to="loc_us-gaap_NoncompeteAgreementsMember_71e6b1b5-9e71-44cb-ae04-89be13df88c9" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/AcquisitionsandDispositionsSummaryofKeyFinancialInformationFromDisposalofHarscoIndustrialSegmentDetailsDetails" xlink:type="simple" xlink:href="hsc-20211231.xsd#AcquisitionsandDispositionsSummaryofKeyFinancialInformationFromDisposalofHarscoIndustrialSegmentDetailsDetails"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/AcquisitionsandDispositionsSummaryofKeyFinancialInformationFromDisposalofHarscoIndustrialSegmentDetailsDetails" xlink:type="extended" id="i3f5177b39cd248d58153be8a42715610_AcquisitionsandDispositionsSummaryofKeyFinancialInformationFromDisposalofHarscoIndustrialSegmentDetailsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_91c0199b-8e32-459c-908b-602b31a964cf" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue_983164dc-3fec-499a-9947-c7fdaffef005" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_91c0199b-8e32-459c-908b-602b31a964cf" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue_983164dc-3fec-499a-9947-c7fdaffef005" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationCostsOfGoodsSold_9a740aed-9746-450a-8192-dfeb176784a5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationCostsOfGoodsSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_91c0199b-8e32-459c-908b-602b31a964cf" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationCostsOfGoodsSold_9a740aed-9746-450a-8192-dfeb176784a5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationBeforeIncomeTax_3d2d6a68-4759-4480-9e12-2be52aeb4daf" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationBeforeIncomeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_91c0199b-8e32-459c-908b-602b31a964cf" xlink:to="loc_us-gaap_DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationBeforeIncomeTax_3d2d6a68-4759-4480-9e12-2be52aeb4daf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax_e3f20ece-383d-4b89-8711-a8710a0ce243" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_91c0199b-8e32-459c-908b-602b31a964cf" xlink:to="loc_us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax_e3f20ece-383d-4b89-8711-a8710a0ce243" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationGeneralAndAdministrativeExpense_ac1d311f-2b05-4cf5-ba37-53f718e8a929" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationGeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_91c0199b-8e32-459c-908b-602b31a964cf" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationGeneralAndAdministrativeExpense_ac1d311f-2b05-4cf5-ba37-53f718e8a929" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationInterestExpense_80d7ea40-1232-4670-ae33-1f0d8177c80f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationInterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_91c0199b-8e32-459c-908b-602b31a964cf" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationInterestExpense_80d7ea40-1232-4670-ae33-1f0d8177c80f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_2f508350-8702-4a5c-89e8-5e14a8b2df58" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_91c0199b-8e32-459c-908b-602b31a964cf" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_2f508350-8702-4a5c-89e8-5e14a8b2df58" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnDiscontinuationOfCashFlowHedgeDueToForecastedTransactionProbableOfNotOccurringNet_2651e5a2-39e9-4c57-8011-b761029f44f1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GainLossOnDiscontinuationOfCashFlowHedgeDueToForecastedTransactionProbableOfNotOccurringNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_91c0199b-8e32-459c-908b-602b31a964cf" xlink:to="loc_us-gaap_GainLossOnDiscontinuationOfCashFlowHedgeDueToForecastedTransactionProbableOfNotOccurringNet_2651e5a2-39e9-4c57-8011-b761029f44f1" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_3346ef20-7754-40f1-bdf4-ca9396f4898d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_91c0199b-8e32-459c-908b-602b31a964cf" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_3346ef20-7754-40f1-bdf4-ca9396f4898d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_a6274c50-48c7-4b4f-88cb-63da210264c8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_3346ef20-7754-40f1-bdf4-ca9396f4898d" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_a6274c50-48c7-4b4f-88cb-63da210264c8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_a6274c50-48c7-4b4f-88cb-63da210264c8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_a6274c50-48c7-4b4f-88cb-63da210264c8" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_a6274c50-48c7-4b4f-88cb-63da210264c8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_11ce1449-7f63-4af6-b287-8c7ba27152fa" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_a6274c50-48c7-4b4f-88cb-63da210264c8" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_11ce1449-7f63-4af6-b287-8c7ba27152fa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_de1eb6bb-ed31-4714-8136-08c7efe81232" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_11ce1449-7f63-4af6-b287-8c7ba27152fa" xlink:to="loc_us-gaap_InterestRateSwapMember_de1eb6bb-ed31-4714-8136-08c7efe81232" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_2ea50c53-908e-49e7-8c4e-338c959cc8f2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_3346ef20-7754-40f1-bdf4-ca9396f4898d" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_2ea50c53-908e-49e7-8c4e-338c959cc8f2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_2ea50c53-908e-49e7-8c4e-338c959cc8f2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_2ea50c53-908e-49e7-8c4e-338c959cc8f2" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_2ea50c53-908e-49e7-8c4e-338c959cc8f2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_fd59b7c7-5b5c-41d9-9040-94a60b815790" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_2ea50c53-908e-49e7-8c4e-338c959cc8f2" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_fd59b7c7-5b5c-41d9-9040-94a60b815790" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_AirCooledHeatExchangersMember_2ff96de0-a1f2-4a49-a1de-1aaa81812406" xlink:href="hsc-20211231.xsd#hsc_AirCooledHeatExchangersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_fd59b7c7-5b5c-41d9-9040-94a60b815790" xlink:to="loc_hsc_AirCooledHeatExchangersMember_2ff96de0-a1f2-4a49-a1de-1aaa81812406" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoIndustrialMember_13051723-ceb8-4c4d-b3d6-81a8bb9130e6" xlink:href="hsc-20211231.xsd#hsc_HarscoIndustrialMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_fd59b7c7-5b5c-41d9-9040-94a60b815790" xlink:to="loc_hsc_HarscoIndustrialMember_13051723-ceb8-4c4d-b3d6-81a8bb9130e6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_8aa9e5be-73ff-4fb2-abfc-cba5f590a8b2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_3346ef20-7754-40f1-bdf4-ca9396f4898d" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_8aa9e5be-73ff-4fb2-abfc-cba5f590a8b2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_8aa9e5be-73ff-4fb2-abfc-cba5f590a8b2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_8aa9e5be-73ff-4fb2-abfc-cba5f590a8b2" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_8aa9e5be-73ff-4fb2-abfc-cba5f590a8b2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_420dc573-00a4-407c-8123-c67ec6a4a3b4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_8aa9e5be-73ff-4fb2-abfc-cba5f590a8b2" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_420dc573-00a4-407c-8123-c67ec6a4a3b4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationsHeldforsaleMember_a95280b1-93c2-45bd-b113-f133702984ce" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DiscontinuedOperationsHeldforsaleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_420dc573-00a4-407c-8123-c67ec6a4a3b4" xlink:to="loc_us-gaap_DiscontinuedOperationsHeldforsaleMember_a95280b1-93c2-45bd-b113-f133702984ce" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_07d5d7b1-26e9-4949-9b65-5bcf7e549535" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_3346ef20-7754-40f1-bdf4-ca9396f4898d" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_07d5d7b1-26e9-4949-9b65-5bcf7e549535" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_07d5d7b1-26e9-4949-9b65-5bcf7e549535_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_07d5d7b1-26e9-4949-9b65-5bcf7e549535" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_07d5d7b1-26e9-4949-9b65-5bcf7e549535_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_8c1bc331-c87c-46bb-bbf1-a17cfe350b10" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_07d5d7b1-26e9-4949-9b65-5bcf7e549535" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_8c1bc331-c87c-46bb-bbf1-a17cfe350b10" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationMember_e991edb1-c81f-4fa1-8db3-fe1d0b957a4c" xlink:href="hsc-20211231.xsd#hsc_DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_8c1bc331-c87c-46bb-bbf1-a17cfe350b10" xlink:to="loc_hsc_DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationMember_e991edb1-c81f-4fa1-8db3-fe1d0b957a4c" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/AcquisitionsandDispositionsSummaryofCashFlowInformationFromDisposalofHarscoIndustrialSegmentDetails" xlink:type="simple" xlink:href="hsc-20211231.xsd#AcquisitionsandDispositionsSummaryofCashFlowInformationFromDisposalofHarscoIndustrialSegmentDetails"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/AcquisitionsandDispositionsSummaryofCashFlowInformationFromDisposalofHarscoIndustrialSegmentDetails" xlink:type="extended" id="i83867aae1d054aabb9ac27189f881724_AcquisitionsandDispositionsSummaryofCashFlowInformationFromDisposalofHarscoIndustrialSegmentDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_a9bf9fcd-513c-4a2b-b662-b5a6922d54b1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationAndAmortizationDiscontinuedOperations_bed77d2f-625f-47c0-883a-5ae49f14a763" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DepreciationAndAmortizationDiscontinuedOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_a9bf9fcd-513c-4a2b-b662-b5a6922d54b1" xlink:to="loc_us-gaap_DepreciationAndAmortizationDiscontinuedOperations_bed77d2f-625f-47c0-883a-5ae49f14a763" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalExpenditureDiscontinuedOperations_2b49d063-2d3c-4705-b5d6-602e07b53fbc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CapitalExpenditureDiscontinuedOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_a9bf9fcd-513c-4a2b-b662-b5a6922d54b1" xlink:to="loc_us-gaap_CapitalExpenditureDiscontinuedOperations_2b49d063-2d3c-4705-b5d6-602e07b53fbc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_68d3fcba-7f0b-43ec-b499-6c662c4af427" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_a9bf9fcd-513c-4a2b-b662-b5a6922d54b1" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_68d3fcba-7f0b-43ec-b499-6c662c4af427" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_54091e9b-ab24-43c5-91c3-3033e2abfbec" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_68d3fcba-7f0b-43ec-b499-6c662c4af427" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_54091e9b-ab24-43c5-91c3-3033e2abfbec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_54091e9b-ab24-43c5-91c3-3033e2abfbec_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_54091e9b-ab24-43c5-91c3-3033e2abfbec" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_54091e9b-ab24-43c5-91c3-3033e2abfbec_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_a6401250-f6be-479f-9e4c-630e1333090c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_54091e9b-ab24-43c5-91c3-3033e2abfbec" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_a6401250-f6be-479f-9e4c-630e1333090c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationsHeldforsaleMember_8285b346-01fd-4350-9558-88be7cc8ab8b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DiscontinuedOperationsHeldforsaleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_a6401250-f6be-479f-9e4c-630e1333090c" xlink:to="loc_us-gaap_DiscontinuedOperationsHeldforsaleMember_8285b346-01fd-4350-9558-88be7cc8ab8b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_37a26c9d-582f-4c2e-872e-b6530db90c2b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_68d3fcba-7f0b-43ec-b499-6c662c4af427" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_37a26c9d-582f-4c2e-872e-b6530db90c2b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_37a26c9d-582f-4c2e-872e-b6530db90c2b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_37a26c9d-582f-4c2e-872e-b6530db90c2b" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_37a26c9d-582f-4c2e-872e-b6530db90c2b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_00784b0a-8739-48ce-80ad-8a3a50af7c19" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_37a26c9d-582f-4c2e-872e-b6530db90c2b" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_00784b0a-8739-48ce-80ad-8a3a50af7c19" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoIndustrialMember_800cbd8b-8d6e-4c77-886e-078de2de23c4" xlink:href="hsc-20211231.xsd#hsc_HarscoIndustrialMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_00784b0a-8739-48ce-80ad-8a3a50af7c19" xlink:to="loc_hsc_HarscoIndustrialMember_800cbd8b-8d6e-4c77-886e-078de2de23c4" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/AccountsReceivableandNoteReceivableDetails" xlink:type="simple" xlink:href="hsc-20211231.xsd#AccountsReceivableandNoteReceivableDetails"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/AccountsReceivableandNoteReceivableDetails" xlink:type="extended" id="i1b1b491709ab4f8c867097d90e40568f_AccountsReceivableandNoteReceivableDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_ca343c16-468a-4976-8504-37a7ca1f9280" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccountsNotesAndLoansReceivableLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableGrossCurrent_f9829f79-9981-4805-a5c5-c8dd1d93d2ce" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccountsReceivableGrossCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_ca343c16-468a-4976-8504-37a7ca1f9280" xlink:to="loc_us-gaap_AccountsReceivableGrossCurrent_f9829f79-9981-4805-a5c5-c8dd1d93d2ce" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_AccountsReceivableGreaterThan12MonthsReserved_f66c5a38-5caf-457b-bfef-9d3920f485af" xlink:href="hsc-20211231.xsd#hsc_AccountsReceivableGreaterThan12MonthsReserved"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_ca343c16-468a-4976-8504-37a7ca1f9280" xlink:to="loc_hsc_AccountsReceivableGreaterThan12MonthsReserved_f66c5a38-5caf-457b-bfef-9d3920f485af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration_dacfed61-9fb1-425f-8179-3dd88d2fb4e5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_ca343c16-468a-4976-8504-37a7ca1f9280" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration_dacfed61-9fb1-425f-8179-3dd88d2fb4e5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableWithImputedInterestFaceAmount_ab5485d0-6c84-4cda-8a38-8921f9f5e372" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ReceivableWithImputedInterestFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_ca343c16-468a-4976-8504-37a7ca1f9280" xlink:to="loc_us-gaap_ReceivableWithImputedInterestFaceAmount_ab5485d0-6c84-4cda-8a38-8921f9f5e372" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_NoteReceivableInterestRateStatedpercentage_5f21b24b-9bbc-4333-aa62-f8e6da98ea86" xlink:href="hsc-20211231.xsd#hsc_NoteReceivableInterestRateStatedpercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_ca343c16-468a-4976-8504-37a7ca1f9280" xlink:to="loc_hsc_NoteReceivableInterestRateStatedpercentage_5f21b24b-9bbc-4333-aa62-f8e6da98ea86" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivablesFairValueDisclosure_a085f4c0-5b92-4878-9900-b406995ade6b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ReceivablesFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_ca343c16-468a-4976-8504-37a7ca1f9280" xlink:to="loc_us-gaap_ReceivablesFairValueDisclosure_a085f4c0-5b92-4878-9900-b406995ade6b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromCollectionOfNotesReceivable_1617161d-acb3-40d7-9553-239f33f8ac2b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProceedsFromCollectionOfNotesReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_ca343c16-468a-4976-8504-37a7ca1f9280" xlink:to="loc_us-gaap_ProceedsFromCollectionOfNotesReceivable_1617161d-acb3-40d7-9553-239f33f8ac2b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableWithImputedInterestNetAmount_3a4efeb3-a9a3-4123-a399-e51ab7c5bb18" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ReceivableWithImputedInterestNetAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_ca343c16-468a-4976-8504-37a7ca1f9280" xlink:to="loc_us-gaap_ReceivableWithImputedInterestNetAmount_3a4efeb3-a9a3-4123-a399-e51ab7c5bb18" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_c1121b1f-b522-47c5-8b43-4430f72d0b25" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_ca343c16-468a-4976-8504-37a7ca1f9280" xlink:to="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_c1121b1f-b522-47c5-8b43-4430f72d0b25" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_fb80c62e-7a39-4f69-9f4f-4edeb65e8a07" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_c1121b1f-b522-47c5-8b43-4430f72d0b25" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_fb80c62e-7a39-4f69-9f4f-4edeb65e8a07" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_fb80c62e-7a39-4f69-9f4f-4edeb65e8a07_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_fb80c62e-7a39-4f69-9f4f-4edeb65e8a07" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_fb80c62e-7a39-4f69-9f4f-4edeb65e8a07_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_7b67d1ce-263a-4b6a-95ea-ebd845ca9d29" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_fb80c62e-7a39-4f69-9f4f-4edeb65e8a07" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_7b67d1ce-263a-4b6a-95ea-ebd845ca9d29" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoIndustrialIKGMember_d7a41df0-e2fc-4317-9e3f-11a257af2954" xlink:href="hsc-20211231.xsd#hsc_HarscoIndustrialIKGMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_7b67d1ce-263a-4b6a-95ea-ebd845ca9d29" xlink:to="loc_hsc_HarscoIndustrialIKGMember_d7a41df0-e2fc-4317-9e3f-11a257af2954" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_2d090fad-509e-4c6d-8250-87ad4b51e7d3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_c1121b1f-b522-47c5-8b43-4430f72d0b25" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_2d090fad-509e-4c6d-8250-87ad4b51e7d3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_2d090fad-509e-4c6d-8250-87ad4b51e7d3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_2d090fad-509e-4c6d-8250-87ad4b51e7d3" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_2d090fad-509e-4c6d-8250-87ad4b51e7d3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_2ad3fa8f-c2a1-4632-8b21-af498f78b37f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_2d090fad-509e-4c6d-8250-87ad4b51e7d3" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_2ad3fa8f-c2a1-4632-8b21-af498f78b37f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_524e112f-0b4e-47b7-934a-a676333438ad" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_2ad3fa8f-c2a1-4632-8b21-af498f78b37f" xlink:to="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_524e112f-0b4e-47b7-934a-a676333438ad" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_AccountsReceivableAgingAxis_616ee254-e0b9-4b4e-af5a-bde723978c91" xlink:href="hsc-20211231.xsd#hsc_AccountsReceivableAgingAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_c1121b1f-b522-47c5-8b43-4430f72d0b25" xlink:to="loc_hsc_AccountsReceivableAgingAxis_616ee254-e0b9-4b4e-af5a-bde723978c91" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_AccountsReceivableAgingDomain_616ee254-e0b9-4b4e-af5a-bde723978c91_default" xlink:href="hsc-20211231.xsd#hsc_AccountsReceivableAgingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_hsc_AccountsReceivableAgingAxis_616ee254-e0b9-4b4e-af5a-bde723978c91" xlink:to="loc_hsc_AccountsReceivableAgingDomain_616ee254-e0b9-4b4e-af5a-bde723978c91_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_AccountsReceivableAgingDomain_8077d479-cb36-41c3-9416-8ac863c7ad27" xlink:href="hsc-20211231.xsd#hsc_AccountsReceivableAgingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_hsc_AccountsReceivableAgingAxis_616ee254-e0b9-4b4e-af5a-bde723978c91" xlink:to="loc_hsc_AccountsReceivableAgingDomain_8077d479-cb36-41c3-9416-8ac863c7ad27" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_Greaterthan12monthsMember_ea91fa8c-db13-4c82-bb9f-d89b16ecd145" xlink:href="hsc-20211231.xsd#hsc_Greaterthan12monthsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hsc_AccountsReceivableAgingDomain_8077d479-cb36-41c3-9416-8ac863c7ad27" xlink:to="loc_hsc_Greaterthan12monthsMember_ea91fa8c-db13-4c82-bb9f-d89b16ecd145" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/PropertyPlantandEquipmentDetails" xlink:type="simple" xlink:href="hsc-20211231.xsd#PropertyPlantandEquipmentDetails"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/PropertyPlantandEquipmentDetails" xlink:type="extended" id="idc1009ee67ce400ba540bedb242b8515_PropertyPlantandEquipmentDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_45f90359-eb57-47d0-94de-6301739f8dd8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_764cf408-da48-4276-9a7e-8694b641deba" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_45f90359-eb57-47d0-94de-6301739f8dd8" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_764cf408-da48-4276-9a7e-8694b641deba" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_eb530fc7-c38b-4f39-8ff3-20f631c95edd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_45f90359-eb57-47d0-94de-6301739f8dd8" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_eb530fc7-c38b-4f39-8ff3-20f631c95edd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_949f69c8-c9ba-463a-a740-13f7b87d176f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_45f90359-eb57-47d0-94de-6301739f8dd8" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_949f69c8-c9ba-463a-a740-13f7b87d176f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_2f00c34d-1479-4546-aa70-9a8e7662ce65" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_45f90359-eb57-47d0-94de-6301739f8dd8" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_2f00c34d-1479-4546-aa70-9a8e7662ce65" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_d406d429-a03e-4d31-b6ee-e6c87145d8c9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_45f90359-eb57-47d0-94de-6301739f8dd8" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_d406d429-a03e-4d31-b6ee-e6c87145d8c9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_a6c5dce7-5461-4f82-96a6-5f826fc28999" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_d406d429-a03e-4d31-b6ee-e6c87145d8c9" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_a6c5dce7-5461-4f82-96a6-5f826fc28999" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_a6c5dce7-5461-4f82-96a6-5f826fc28999_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_a6c5dce7-5461-4f82-96a6-5f826fc28999" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_a6c5dce7-5461-4f82-96a6-5f826fc28999_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_581539b1-bc7e-4727-964b-be5b1e920904" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_a6c5dce7-5461-4f82-96a6-5f826fc28999" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_581539b1-bc7e-4727-964b-be5b1e920904" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LandMember_5e99fb2c-1add-4d80-ad59-508e77d76c12" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LandMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_581539b1-bc7e-4727-964b-be5b1e920904" xlink:to="loc_us-gaap_LandMember_5e99fb2c-1add-4d80-ad59-508e77d76c12" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LandImprovementsMember_2e832d52-9984-4351-bde1-9f8ab0e7ef13" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LandImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_581539b1-bc7e-4727-964b-be5b1e920904" xlink:to="loc_us-gaap_LandImprovementsMember_2e832d52-9984-4351-bde1-9f8ab0e7ef13" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BuildingAndBuildingImprovementsMember_ace1ebf9-8027-48fc-8b29-10ad0edba51c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BuildingAndBuildingImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_581539b1-bc7e-4727-964b-be5b1e920904" xlink:to="loc_us-gaap_BuildingAndBuildingImprovementsMember_ace1ebf9-8027-48fc-8b29-10ad0edba51c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MachineryAndEquipmentMember_0b8f9a35-b2a7-468c-8b4d-f072e2c35a4d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MachineryAndEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_581539b1-bc7e-4727-964b-be5b1e920904" xlink:to="loc_us-gaap_MachineryAndEquipmentMember_0b8f9a35-b2a7-468c-8b4d-f072e2c35a4d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConstructionInProgressMember_622fdc73-52ad-42e4-80eb-ad48ff333389" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ConstructionInProgressMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_581539b1-bc7e-4727-964b-be5b1e920904" xlink:to="loc_us-gaap_ConstructionInProgressMember_622fdc73-52ad-42e4-80eb-ad48ff333389" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_4c2dac3e-3ebe-4e61-a23f-eefc786cf87c" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_d406d429-a03e-4d31-b6ee-e6c87145d8c9" xlink:to="loc_srt_RangeAxis_4c2dac3e-3ebe-4e61-a23f-eefc786cf87c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_4c2dac3e-3ebe-4e61-a23f-eefc786cf87c_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_4c2dac3e-3ebe-4e61-a23f-eefc786cf87c" xlink:to="loc_srt_RangeMember_4c2dac3e-3ebe-4e61-a23f-eefc786cf87c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_f4b8a819-92f9-4f69-8ba2-fe9985ee5508" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_4c2dac3e-3ebe-4e61-a23f-eefc786cf87c" xlink:to="loc_srt_RangeMember_f4b8a819-92f9-4f69-8ba2-fe9985ee5508" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_c5253a6d-e6ed-434f-a590-4bd73dc123c0" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_f4b8a819-92f9-4f69-8ba2-fe9985ee5508" xlink:to="loc_srt_MinimumMember_c5253a6d-e6ed-434f-a590-4bd73dc123c0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_fdb98ae0-adc2-466a-9b4b-4ed5e0ca7dd9" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_f4b8a819-92f9-4f69-8ba2-fe9985ee5508" xlink:to="loc_srt_MaximumMember_fdb98ae0-adc2-466a-9b4b-4ed5e0ca7dd9" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/PropertyPlantandEquipmentNarrativeDetails" xlink:type="simple" xlink:href="hsc-20211231.xsd#PropertyPlantandEquipmentNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/PropertyPlantandEquipmentNarrativeDetails" xlink:type="extended" id="i2340edea7bc14ddd9707f267816cc762_PropertyPlantandEquipmentNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_0d49e658-32e5-45b1-8406-2dfae1bc0324" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_895dda0d-52cd-4374-a5ff-7b06908a0079" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_0d49e658-32e5-45b1-8406-2dfae1bc0324" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_895dda0d-52cd-4374-a5ff-7b06908a0079" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_87fe20ef-0bac-4491-b55f-a1a5dd89a1fa" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_0d49e658-32e5-45b1-8406-2dfae1bc0324" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_87fe20ef-0bac-4491-b55f-a1a5dd89a1fa" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_69858e6b-f343-42a5-94a4-dd9cb5382cf9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_87fe20ef-0bac-4491-b55f-a1a5dd89a1fa" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_69858e6b-f343-42a5-94a4-dd9cb5382cf9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_69858e6b-f343-42a5-94a4-dd9cb5382cf9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_69858e6b-f343-42a5-94a4-dd9cb5382cf9" xlink:to="loc_us-gaap_SegmentDomain_69858e6b-f343-42a5-94a4-dd9cb5382cf9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_0b78bad1-0152-4800-ba50-f2a69eedc6e6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_69858e6b-f343-42a5-94a4-dd9cb5382cf9" xlink:to="loc_us-gaap_SegmentDomain_0b78bad1-0152-4800-ba50-f2a69eedc6e6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoEnvironmentalSegmentMember_6178cc78-6a31-4417-ad37-d94295d5bb53" xlink:href="hsc-20211231.xsd#hsc_HarscoEnvironmentalSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_0b78bad1-0152-4800-ba50-f2a69eedc6e6" xlink:to="loc_hsc_HarscoEnvironmentalSegmentMember_6178cc78-6a31-4417-ad37-d94295d5bb53" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_22e59510-d74f-4c1d-b239-6c8bfc79cec9" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_87fe20ef-0bac-4491-b55f-a1a5dd89a1fa" xlink:to="loc_srt_StatementGeographicalAxis_22e59510-d74f-4c1d-b239-6c8bfc79cec9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_22e59510-d74f-4c1d-b239-6c8bfc79cec9_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_22e59510-d74f-4c1d-b239-6c8bfc79cec9" xlink:to="loc_srt_SegmentGeographicalDomain_22e59510-d74f-4c1d-b239-6c8bfc79cec9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_bc85bc46-0a05-497d-8f12-577a81bec447" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_22e59510-d74f-4c1d-b239-6c8bfc79cec9" xlink:to="loc_srt_SegmentGeographicalDomain_bc85bc46-0a05-497d-8f12-577a81bec447" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_CN_400d68b4-067e-4fc4-8c89-188ebb40f77b" xlink:href="https://xbrl.sec.gov/country/2021/country-2021.xsd#country_CN"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_bc85bc46-0a05-497d-8f12-577a81bec447" xlink:to="loc_country_CN_400d68b4-067e-4fc4-8c89-188ebb40f77b" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/GoodwillandOtherIntangibleAssetsDetails" xlink:type="simple" xlink:href="hsc-20211231.xsd#GoodwillandOtherIntangibleAssetsDetails"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/GoodwillandOtherIntangibleAssetsDetails" xlink:type="extended" id="i45a0191c2e8e4d24b3fab2c279a1b452_GoodwillandOtherIntangibleAssetsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillLineItems_ff967c47-196b-4dbb-8e02-7459b9912b4d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GoodwillLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillRollForward_6cebb81d-1445-4fee-92bf-675d5f0aef68" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GoodwillRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_ff967c47-196b-4dbb-8e02-7459b9912b4d" xlink:to="loc_us-gaap_GoodwillRollForward_6cebb81d-1445-4fee-92bf-675d5f0aef68" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_8f3e6904-788e-439e-9630-375b7d942a0e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_6cebb81d-1445-4fee-92bf-675d5f0aef68" xlink:to="loc_us-gaap_Goodwill_8f3e6904-788e-439e-9630-375b7d942a0e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillOtherIncreaseDecrease_bf19b5f1-f241-4f5b-ab83-1e4467d5d7f1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GoodwillOtherIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_6cebb81d-1445-4fee-92bf-675d5f0aef68" xlink:to="loc_us-gaap_GoodwillOtherIncreaseDecrease_bf19b5f1-f241-4f5b-ab83-1e4467d5d7f1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillForeignCurrencyTranslationGainLoss_301adeea-180e-4ae6-a53f-9a1e74cb1891" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GoodwillForeignCurrencyTranslationGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_6cebb81d-1445-4fee-92bf-675d5f0aef68" xlink:to="loc_us-gaap_GoodwillForeignCurrencyTranslationGainLoss_301adeea-180e-4ae6-a53f-9a1e74cb1891" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_eb526e97-5457-40c9-a185-ee358ad9b191" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_Goodwill"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_ba9b0f87-b1bd-4e6a-8f36-df7fe25eac3f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfGoodwillTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_ff967c47-196b-4dbb-8e02-7459b9912b4d" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_ba9b0f87-b1bd-4e6a-8f36-df7fe25eac3f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_a6ff10fd-4101-4ce4-ab65-4524fd17d210" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_ba9b0f87-b1bd-4e6a-8f36-df7fe25eac3f" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_a6ff10fd-4101-4ce4-ab65-4524fd17d210" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_a6ff10fd-4101-4ce4-ab65-4524fd17d210_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_a6ff10fd-4101-4ce4-ab65-4524fd17d210" xlink:to="loc_us-gaap_SegmentDomain_a6ff10fd-4101-4ce4-ab65-4524fd17d210_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_e4064a31-e8c6-4613-ad52-566e86be0dec" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_a6ff10fd-4101-4ce4-ab65-4524fd17d210" xlink:to="loc_us-gaap_SegmentDomain_e4064a31-e8c6-4613-ad52-566e86be0dec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoEnvironmentalSegmentMember_d72b33cf-7d68-4f1e-892d-c6f60cd9d9a1" xlink:href="hsc-20211231.xsd#hsc_HarscoEnvironmentalSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_e4064a31-e8c6-4613-ad52-566e86be0dec" xlink:to="loc_hsc_HarscoEnvironmentalSegmentMember_d72b33cf-7d68-4f1e-892d-c6f60cd9d9a1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_CleanEarthMember_0d5b98f3-e6eb-4211-9bce-eda8615061dd" xlink:href="hsc-20211231.xsd#hsc_CleanEarthMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_e4064a31-e8c6-4613-ad52-566e86be0dec" xlink:to="loc_hsc_CleanEarthMember_0d5b98f3-e6eb-4211-9bce-eda8615061dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoRailMember_d245982d-f195-4062-80a3-145bad2923b5" xlink:href="hsc-20211231.xsd#hsc_HarscoRailMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_e4064a31-e8c6-4613-ad52-566e86be0dec" xlink:to="loc_hsc_HarscoRailMember_d245982d-f195-4062-80a3-145bad2923b5" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/GoodwillandOtherIntangibleAssetsDetails2" xlink:type="simple" xlink:href="hsc-20211231.xsd#GoodwillandOtherIntangibleAssetsDetails2"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/GoodwillandOtherIntangibleAssetsDetails2" xlink:type="extended" id="ic2d677f155c442c3b450f7f086517db5_GoodwillandOtherIntangibleAssetsDetails2">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_32058c6e-6dff-4235-8b5e-190ab2b1f02d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_0ac762d8-359f-48af-8166-28750991fa75" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_32058c6e-6dff-4235-8b5e-190ab2b1f02d" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_0ac762d8-359f-48af-8166-28750991fa75" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_53f1f563-3d6c-4380-ab87-e1f54f058c76" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_32058c6e-6dff-4235-8b5e-190ab2b1f02d" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_53f1f563-3d6c-4380-ab87-e1f54f058c76" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_cb7fd2ee-ebcc-4f1d-88e7-0d95c498cb23" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_32058c6e-6dff-4235-8b5e-190ab2b1f02d" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_cb7fd2ee-ebcc-4f1d-88e7-0d95c498cb23" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_1713822a-beb3-478f-afcf-f086bd719620" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_32058c6e-6dff-4235-8b5e-190ab2b1f02d" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_1713822a-beb3-478f-afcf-f086bd719620" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_a71e9b7e-5db8-4dbd-98bf-49a58037259f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_32058c6e-6dff-4235-8b5e-190ab2b1f02d" xlink:to="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_a71e9b7e-5db8-4dbd-98bf-49a58037259f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_b3eaeddc-00d8-4c7e-a889-ac354ae96ba4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_a71e9b7e-5db8-4dbd-98bf-49a58037259f" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_b3eaeddc-00d8-4c7e-a889-ac354ae96ba4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_b3eaeddc-00d8-4c7e-a889-ac354ae96ba4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_b3eaeddc-00d8-4c7e-a889-ac354ae96ba4" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_b3eaeddc-00d8-4c7e-a889-ac354ae96ba4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_e0ab9005-8e43-436d-bd5a-734fc3e2e05a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_b3eaeddc-00d8-4c7e-a889-ac354ae96ba4" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_e0ab9005-8e43-436d-bd5a-734fc3e2e05a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelatedIntangibleAssetsMember_b27fb86f-1fab-4727-8ffe-22b05d2dbe88" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CustomerRelatedIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_e0ab9005-8e43-436d-bd5a-734fc3e2e05a" xlink:to="loc_us-gaap_CustomerRelatedIntangibleAssetsMember_b27fb86f-1fab-4727-8ffe-22b05d2dbe88" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_PermitsAndRightsMember_30948028-3ae8-4d2f-9160-5238be18cd61" xlink:href="hsc-20211231.xsd#hsc_PermitsAndRightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_e0ab9005-8e43-436d-bd5a-734fc3e2e05a" xlink:to="loc_hsc_PermitsAndRightsMember_30948028-3ae8-4d2f-9160-5238be18cd61" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnpatentedTechnologyMember_d789ff5e-291f-4498-b972-0e26b9cc3ccd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_UnpatentedTechnologyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_e0ab9005-8e43-436d-bd5a-734fc3e2e05a" xlink:to="loc_us-gaap_UnpatentedTechnologyMember_d789ff5e-291f-4498-b972-0e26b9cc3ccd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TradeNamesMember_075a2672-8b0a-4691-96ed-b118adee0323" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_e0ab9005-8e43-436d-bd5a-734fc3e2e05a" xlink:to="loc_us-gaap_TradeNamesMember_075a2672-8b0a-4691-96ed-b118adee0323" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_AirRightsMember_a6ce6ee5-cf84-485a-9476-604efbd01058" xlink:href="hsc-20211231.xsd#hsc_AirRightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_e0ab9005-8e43-436d-bd5a-734fc3e2e05a" xlink:to="loc_hsc_AirRightsMember_a6ce6ee5-cf84-485a-9476-604efbd01058" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PatentsMember_ee326b4a-56a8-4e3e-9538-5926e6cc2630" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PatentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_e0ab9005-8e43-436d-bd5a-734fc3e2e05a" xlink:to="loc_us-gaap_PatentsMember_ee326b4a-56a8-4e3e-9538-5926e6cc2630" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_NonCompeteAgreementMember_43acef1d-b8b5-45a6-a7c5-c8ffb595b744" xlink:href="hsc-20211231.xsd#hsc_NonCompeteAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_e0ab9005-8e43-436d-bd5a-734fc3e2e05a" xlink:to="loc_hsc_NonCompeteAgreementMember_43acef1d-b8b5-45a6-a7c5-c8ffb595b744" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIntangibleAssetsMember_232da3a5-5b27-4134-861b-dbcbb37c70de" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_e0ab9005-8e43-436d-bd5a-734fc3e2e05a" xlink:to="loc_us-gaap_OtherIntangibleAssetsMember_232da3a5-5b27-4134-861b-dbcbb37c70de" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/DebtandCreditAgreementsScheduleofLongTermDebtDetails" xlink:type="simple" xlink:href="hsc-20211231.xsd#DebtandCreditAgreementsScheduleofLongTermDebtDetails"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/DebtandCreditAgreementsScheduleofLongTermDebtDetails" xlink:type="extended" id="i94fae324cda0482a94234aa0e6d4267d_DebtandCreditAgreementsScheduleofLongTermDebtDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLineItems_0057bd3b-fe57-4b97-ad0b-95a345186a06" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LineOfCreditFacilityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_56a859ed-cc15-4d07-a229-34028628afef" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_0057bd3b-fe57-4b97-ad0b-95a345186a06" xlink:to="loc_us-gaap_LongTermDebt_56a859ed-cc15-4d07-a229-34028628afef" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_19776acb-c903-4da4-81c5-675208917346" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_0057bd3b-fe57-4b97-ad0b-95a345186a06" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_19776acb-c903-4da4-81c5-675208917346" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtWeightedAverageInterestRate_8b403287-0610-4d1b-a386-4cbf0c9f6538" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtWeightedAverageInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_0057bd3b-fe57-4b97-ad0b-95a345186a06" xlink:to="loc_us-gaap_DebtWeightedAverageInterestRate_8b403287-0610-4d1b-a386-4cbf0c9f6538" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_9c38a135-f2fc-41da-89a3-6768c9df4dfd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_0057bd3b-fe57-4b97-ad0b-95a345186a06" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_9c38a135-f2fc-41da-89a3-6768c9df4dfd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNoncurrentNet_d5e8d203-0a26-410e-91ad-bc1ee9760778" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredFinanceCostsNoncurrentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_0057bd3b-fe57-4b97-ad0b-95a345186a06" xlink:to="loc_us-gaap_DeferredFinanceCostsNoncurrentNet_d5e8d203-0a26-410e-91ad-bc1ee9760778" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent_bb397ebb-d737-468d-8fd7-ed07b994162b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermDebtCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_0057bd3b-fe57-4b97-ad0b-95a345186a06" xlink:to="loc_us-gaap_LongTermDebtCurrent_bb397ebb-d737-468d-8fd7-ed07b994162b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_3338156f-5962-4699-9da5-8fa745ff7ed9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_0057bd3b-fe57-4b97-ad0b-95a345186a06" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_3338156f-5962-4699-9da5-8fa745ff7ed9" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityTable_957192cc-a906-4bc7-89ac-d991216cd9c0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LineOfCreditFacilityTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_0057bd3b-fe57-4b97-ad0b-95a345186a06" xlink:to="loc_us-gaap_LineOfCreditFacilityTable_957192cc-a906-4bc7-89ac-d991216cd9c0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_443fc490-c1bd-4582-8a7a-d8b92a58fe88" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_957192cc-a906-4bc7-89ac-d991216cd9c0" xlink:to="loc_us-gaap_DebtInstrumentAxis_443fc490-c1bd-4582-8a7a-d8b92a58fe88" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_443fc490-c1bd-4582-8a7a-d8b92a58fe88_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_443fc490-c1bd-4582-8a7a-d8b92a58fe88" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_443fc490-c1bd-4582-8a7a-d8b92a58fe88_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_8f74ca47-97bc-4655-b2a8-9375e8868cc4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_443fc490-c1bd-4582-8a7a-d8b92a58fe88" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_8f74ca47-97bc-4655-b2a8-9375e8868cc4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_Notes5Point75PercentDue15May2018Member_21cbf274-8fcc-4250-a3a7-4b19c455574f" xlink:href="hsc-20211231.xsd#hsc_Notes5Point75PercentDue15May2018Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_8f74ca47-97bc-4655-b2a8-9375e8868cc4" xlink:to="loc_hsc_Notes5Point75PercentDue15May2018Member_21cbf274-8fcc-4250-a3a7-4b19c455574f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_b22fdd06-ee44-442d-aced-f71766dfe7c0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_957192cc-a906-4bc7-89ac-d991216cd9c0" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_b22fdd06-ee44-442d-aced-f71766dfe7c0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_b22fdd06-ee44-442d-aced-f71766dfe7c0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_b22fdd06-ee44-442d-aced-f71766dfe7c0" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_b22fdd06-ee44-442d-aced-f71766dfe7c0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_7438a66d-47dc-4d29-bedd-cdbd752a9fe3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_b22fdd06-ee44-442d-aced-f71766dfe7c0" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_7438a66d-47dc-4d29-bedd-cdbd752a9fe3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_NewTermLoanMember_7f36437c-b655-495e-bec6-b9bd1779ceb9" xlink:href="hsc-20211231.xsd#hsc_NewTermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_7438a66d-47dc-4d29-bedd-cdbd752a9fe3" xlink:to="loc_hsc_NewTermLoanMember_7f36437c-b655-495e-bec6-b9bd1779ceb9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_TermLoanAMember_89a8305a-e11f-475a-86d3-f2c53fe6150e" xlink:href="hsc-20211231.xsd#hsc_TermLoanAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_7438a66d-47dc-4d29-bedd-cdbd752a9fe3" xlink:to="loc_hsc_TermLoanAMember_89a8305a-e11f-475a-86d3-f2c53fe6150e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_TermLoanBMember_39cfa8f6-018a-4459-91ec-6ab99d26bce5" xlink:href="hsc-20211231.xsd#hsc_TermLoanBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_7438a66d-47dc-4d29-bedd-cdbd752a9fe3" xlink:to="loc_hsc_TermLoanBMember_39cfa8f6-018a-4459-91ec-6ab99d26bce5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_d670d115-ccda-478a-84e1-1a70d7bea23f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_7438a66d-47dc-4d29-bedd-cdbd752a9fe3" xlink:to="loc_us-gaap_SeniorNotesMember_d670d115-ccda-478a-84e1-1a70d7bea23f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesPayableOtherPayablesMember_4742cd58-09d2-40fc-8ce7-05883bcb6f6f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NotesPayableOtherPayablesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_7438a66d-47dc-4d29-bedd-cdbd752a9fe3" xlink:to="loc_us-gaap_NotesPayableOtherPayablesMember_4742cd58-09d2-40fc-8ce7-05883bcb6f6f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_a10acc25-c771-4167-8978-8d388c26964e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_957192cc-a906-4bc7-89ac-d991216cd9c0" xlink:to="loc_us-gaap_CreditFacilityAxis_a10acc25-c771-4167-8978-8d388c26964e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_a10acc25-c771-4167-8978-8d388c26964e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_a10acc25-c771-4167-8978-8d388c26964e" xlink:to="loc_us-gaap_CreditFacilityDomain_a10acc25-c771-4167-8978-8d388c26964e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_7181d60b-ed49-435e-bbec-8e340cca8d9a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_a10acc25-c771-4167-8978-8d388c26964e" xlink:to="loc_us-gaap_CreditFacilityDomain_7181d60b-ed49-435e-bbec-8e340cca8d9a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_2857ccc9-1dfc-44bc-9b4a-f15eb5316dda" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_7181d60b-ed49-435e-bbec-8e340cca8d9a" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_2857ccc9-1dfc-44bc-9b4a-f15eb5316dda" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/DebtandCreditAgreementsNarrativeDetails" xlink:type="simple" xlink:href="hsc-20211231.xsd#DebtandCreditAgreementsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/DebtandCreditAgreementsNarrativeDetails" xlink:type="extended" id="id1bf097850c443cc96aed028d0969617_DebtandCreditAgreementsNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLineItems_d74d91e9-95db-40e9-b6b7-448b48915651" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LineOfCreditFacilityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestPaid_0013dc46-2d90-4f3d-b9eb-9e601805992e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InterestPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_d74d91e9-95db-40e9-b6b7-448b48915651" xlink:to="loc_us-gaap_InterestPaid_0013dc46-2d90-4f3d-b9eb-9e601805992e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_NetDebtToConsolidatedAdjustedEBITDARatioCovenant_838bc270-c69c-4214-b7af-270f101c69c3" xlink:href="hsc-20211231.xsd#hsc_NetDebtToConsolidatedAdjustedEBITDARatioCovenant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_d74d91e9-95db-40e9-b6b7-448b48915651" xlink:to="loc_hsc_NetDebtToConsolidatedAdjustedEBITDARatioCovenant_838bc270-c69c-4214-b7af-270f101c69c3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_7266c6db-09f2-43ff-801c-b04b77f0db52" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_d74d91e9-95db-40e9-b6b7-448b48915651" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_7266c6db-09f2-43ff-801c-b04b77f0db52" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_87d08749-6d95-4396-ad00-afca6650accb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_d74d91e9-95db-40e9-b6b7-448b48915651" xlink:to="loc_us-gaap_LongTermDebt_87d08749-6d95-4396-ad00-afca6650accb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNoncurrentNet_f8be63a9-c074-44bd-9bac-7b3781ba9359" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredFinanceCostsNoncurrentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_d74d91e9-95db-40e9-b6b7-448b48915651" xlink:to="loc_us-gaap_DeferredFinanceCostsNoncurrentNet_f8be63a9-c074-44bd-9bac-7b3781ba9359" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_cefeddfc-f4e8-4942-b3d0-7e694282f19f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_d74d91e9-95db-40e9-b6b7-448b48915651" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_cefeddfc-f4e8-4942-b3d0-7e694282f19f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DebtInstrumentBasisSpreadOnVariableRateFloor_8297a36d-e041-48a7-bad1-e6c62448788b" xlink:href="hsc-20211231.xsd#hsc_DebtInstrumentBasisSpreadOnVariableRateFloor"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_d74d91e9-95db-40e9-b6b7-448b48915651" xlink:to="loc_hsc_DebtInstrumentBasisSpreadOnVariableRateFloor_8297a36d-e041-48a7-bad1-e6c62448788b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_0f633d6f-44cf-49c7-b926-9cf2c3893b85" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_d74d91e9-95db-40e9-b6b7-448b48915651" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_0f633d6f-44cf-49c7-b926-9cf2c3893b85" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_fb6a4989-653f-486a-a102-9ef11c505689" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WriteOffOfDeferredDebtIssuanceCost_fd9db6b5-5a2f-4b5c-a6a1-5ab4c3a0fda7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_WriteOffOfDeferredDebtIssuanceCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_d74d91e9-95db-40e9-b6b7-448b48915651" xlink:to="loc_us-gaap_WriteOffOfDeferredDebtIssuanceCost_fd9db6b5-5a2f-4b5c-a6a1-5ab4c3a0fda7" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_fb26c540-5c37-409b-bb40-7b68851ffa33" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_d74d91e9-95db-40e9-b6b7-448b48915651" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_fb26c540-5c37-409b-bb40-7b68851ffa33" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfFinancingCosts_946fbac4-d3f3-407d-946f-253e0256aa54" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsOfFinancingCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_d74d91e9-95db-40e9-b6b7-448b48915651" xlink:to="loc_us-gaap_PaymentsOfFinancingCosts_946fbac4-d3f3-407d-946f-253e0256aa54" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermBorrowings_8df26151-daff-4032-be91-cc253157eb43" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShortTermBorrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_d74d91e9-95db-40e9-b6b7-448b48915651" xlink:to="loc_us-gaap_ShortTermBorrowings_8df26151-daff-4032-be91-cc253157eb43" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtWeightedAverageInterestRate_1f0d699d-1cbf-478d-ab1e-d36dceded440" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShortTermDebtWeightedAverageInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_d74d91e9-95db-40e9-b6b7-448b48915651" xlink:to="loc_us-gaap_ShortTermDebtWeightedAverageInterestRate_1f0d699d-1cbf-478d-ab1e-d36dceded440" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DebtInstrumentQuarterlyAmortizationRate_55a366e3-ec55-4898-bb35-4efd3f277939" xlink:href="hsc-20211231.xsd#hsc_DebtInstrumentQuarterlyAmortizationRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_d74d91e9-95db-40e9-b6b7-448b48915651" xlink:to="loc_hsc_DebtInstrumentQuarterlyAmortizationRate_55a366e3-ec55-4898-bb35-4efd3f277939" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts_7f8fb847-6314-44df-a30f-f017ad0b03de" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_d74d91e9-95db-40e9-b6b7-448b48915651" xlink:to="loc_us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts_7f8fb847-6314-44df-a30f-f017ad0b03de" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNet_a5dd08ee-2e38-426b-ac41-f4b16e92f814" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredFinanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_d74d91e9-95db-40e9-b6b7-448b48915651" xlink:to="loc_us-gaap_DeferredFinanceCostsNet_a5dd08ee-2e38-426b-ac41-f4b16e92f814" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_NetDebtToConsolidatedAdjustedEBITDARatioCovenantQuarterlyIncreaseDecrease_2f667e29-aad1-4dda-ab69-bde402c7eb5e" xlink:href="hsc-20211231.xsd#hsc_NetDebtToConsolidatedAdjustedEBITDARatioCovenantQuarterlyIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_d74d91e9-95db-40e9-b6b7-448b48915651" xlink:to="loc_hsc_NetDebtToConsolidatedAdjustedEBITDARatioCovenantQuarterlyIncreaseDecrease_2f667e29-aad1-4dda-ab69-bde402c7eb5e" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_NetDebtToConsolidatedAdjustedEBITDARatioCovenantIncreaseDecreaseRelatedToDivestureOfBusiness_5daacccc-cf5b-4969-9376-d46adb6ec9ca" xlink:href="hsc-20211231.xsd#hsc_NetDebtToConsolidatedAdjustedEBITDARatioCovenantIncreaseDecreaseRelatedToDivestureOfBusiness"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_d74d91e9-95db-40e9-b6b7-448b48915651" xlink:to="loc_hsc_NetDebtToConsolidatedAdjustedEBITDARatioCovenantIncreaseDecreaseRelatedToDivestureOfBusiness_5daacccc-cf5b-4969-9376-d46adb6ec9ca" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ThresholdNetDebtToConsolidatedAdjustedEBITDARatioCovenant_f8173f2f-c2ec-40ae-9ec2-8017a0ef9966" xlink:href="hsc-20211231.xsd#hsc_ThresholdNetDebtToConsolidatedAdjustedEBITDARatioCovenant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_d74d91e9-95db-40e9-b6b7-448b48915651" xlink:to="loc_hsc_ThresholdNetDebtToConsolidatedAdjustedEBITDARatioCovenant_f8173f2f-c2ec-40ae-9ec2-8017a0ef9966" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityTable_98c8f5f6-b561-4e56-848c-019b323871dd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LineOfCreditFacilityTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_d74d91e9-95db-40e9-b6b7-448b48915651" xlink:to="loc_us-gaap_LineOfCreditFacilityTable_98c8f5f6-b561-4e56-848c-019b323871dd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_MaturityPeriodAxis_6ff5509e-7d51-4f8a-b975-3f65666d3fa6" xlink:href="hsc-20211231.xsd#hsc_MaturityPeriodAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_98c8f5f6-b561-4e56-848c-019b323871dd" xlink:to="loc_hsc_MaturityPeriodAxis_6ff5509e-7d51-4f8a-b975-3f65666d3fa6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_MaturityPeriodDomain_6ff5509e-7d51-4f8a-b975-3f65666d3fa6_default" xlink:href="hsc-20211231.xsd#hsc_MaturityPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_hsc_MaturityPeriodAxis_6ff5509e-7d51-4f8a-b975-3f65666d3fa6" xlink:to="loc_hsc_MaturityPeriodDomain_6ff5509e-7d51-4f8a-b975-3f65666d3fa6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_MaturityPeriodDomain_0a8e49b6-43e3-4114-a43e-a74fbf3e492e" xlink:href="hsc-20211231.xsd#hsc_MaturityPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_hsc_MaturityPeriodAxis_6ff5509e-7d51-4f8a-b975-3f65666d3fa6" xlink:to="loc_hsc_MaturityPeriodDomain_0a8e49b6-43e3-4114-a43e-a74fbf3e492e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_f6d63654-b774-40c3-8bff-2d351a9cab8c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_98c8f5f6-b561-4e56-848c-019b323871dd" xlink:to="loc_us-gaap_CreditFacilityAxis_f6d63654-b774-40c3-8bff-2d351a9cab8c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_f6d63654-b774-40c3-8bff-2d351a9cab8c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_f6d63654-b774-40c3-8bff-2d351a9cab8c" xlink:to="loc_us-gaap_CreditFacilityDomain_f6d63654-b774-40c3-8bff-2d351a9cab8c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_d0fc1cbd-f24e-4601-9f44-9ce7f8dcc488" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_f6d63654-b774-40c3-8bff-2d351a9cab8c" xlink:to="loc_us-gaap_CreditFacilityDomain_d0fc1cbd-f24e-4601-9f44-9ce7f8dcc488" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_92c1bcf8-cbfb-4104-b986-0e5ead525a3f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_d0fc1cbd-f24e-4601-9f44-9ce7f8dcc488" xlink:to="loc_us-gaap_LineOfCreditMember_92c1bcf8-cbfb-4104-b986-0e5ead525a3f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_36ed184f-da24-4160-8bad-318bbec0c473" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_d0fc1cbd-f24e-4601-9f44-9ce7f8dcc488" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_36ed184f-da24-4160-8bad-318bbec0c473" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_c433df8d-144c-46c8-aac0-9d3bd3c084de" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_98c8f5f6-b561-4e56-848c-019b323871dd" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_c433df8d-144c-46c8-aac0-9d3bd3c084de" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_c433df8d-144c-46c8-aac0-9d3bd3c084de_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_c433df8d-144c-46c8-aac0-9d3bd3c084de" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_c433df8d-144c-46c8-aac0-9d3bd3c084de_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_346b00b0-3142-46ad-baef-13b986ac0e34" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_c433df8d-144c-46c8-aac0-9d3bd3c084de" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_346b00b0-3142-46ad-baef-13b986ac0e34" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_NewTermLoanMember_8de1c90f-a117-4f1f-8a2f-517460722147" xlink:href="hsc-20211231.xsd#hsc_NewTermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_346b00b0-3142-46ad-baef-13b986ac0e34" xlink:to="loc_hsc_NewTermLoanMember_8de1c90f-a117-4f1f-8a2f-517460722147" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_TermLoanAMember_45b602d7-72c8-48ea-bd19-4db75ca4d32b" xlink:href="hsc-20211231.xsd#hsc_TermLoanAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_346b00b0-3142-46ad-baef-13b986ac0e34" xlink:to="loc_hsc_TermLoanAMember_45b602d7-72c8-48ea-bd19-4db75ca4d32b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_TermLoanBMember_04dc27a8-a7df-47bc-b5df-53f30aa36d93" xlink:href="hsc-20211231.xsd#hsc_TermLoanBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_346b00b0-3142-46ad-baef-13b986ac0e34" xlink:to="loc_hsc_TermLoanBMember_04dc27a8-a7df-47bc-b5df-53f30aa36d93" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_2a77b2a8-7cca-4e80-8d82-bfc0bfe2763f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_346b00b0-3142-46ad-baef-13b986ac0e34" xlink:to="loc_us-gaap_SeniorNotesMember_2a77b2a8-7cca-4e80-8d82-bfc0bfe2763f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesPayableOtherPayablesMember_462f9ca8-c795-4969-8c80-704c5ac225e2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NotesPayableOtherPayablesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_346b00b0-3142-46ad-baef-13b986ac0e34" xlink:to="loc_us-gaap_NotesPayableOtherPayablesMember_462f9ca8-c795-4969-8c80-704c5ac225e2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BridgeLoanMember_d8004994-bd03-45e0-a942-1af039057059" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BridgeLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_346b00b0-3142-46ad-baef-13b986ac0e34" xlink:to="loc_us-gaap_BridgeLoanMember_d8004994-bd03-45e0-a942-1af039057059" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_cfacecfa-1ed0-4f82-8b36-5eab3d535cd6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_98c8f5f6-b561-4e56-848c-019b323871dd" xlink:to="loc_us-gaap_DebtInstrumentAxis_cfacecfa-1ed0-4f82-8b36-5eab3d535cd6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_cfacecfa-1ed0-4f82-8b36-5eab3d535cd6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_cfacecfa-1ed0-4f82-8b36-5eab3d535cd6" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_cfacecfa-1ed0-4f82-8b36-5eab3d535cd6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_cb423bcb-5707-4e97-8b81-afec1d09b30d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_cfacecfa-1ed0-4f82-8b36-5eab3d535cd6" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_cb423bcb-5707-4e97-8b81-afec1d09b30d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_SeniorUnsecuredNotes5.75Due2027Member_8c9c57da-7263-475c-8b18-eaa12a01973e" xlink:href="hsc-20211231.xsd#hsc_SeniorUnsecuredNotes5.75Due2027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_cb423bcb-5707-4e97-8b81-afec1d09b30d" xlink:to="loc_hsc_SeniorUnsecuredNotes5.75Due2027Member_8c9c57da-7263-475c-8b18-eaa12a01973e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_Notes5Point75PercentDue15May2018Member_1ff4001f-09f0-4b47-ace7-0e35b950386d" xlink:href="hsc-20211231.xsd#hsc_Notes5Point75PercentDue15May2018Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_cb423bcb-5707-4e97-8b81-afec1d09b30d" xlink:to="loc_hsc_Notes5Point75PercentDue15May2018Member_1ff4001f-09f0-4b47-ace7-0e35b950386d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_f746b84e-8d00-475f-9592-062742005ebf" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_98c8f5f6-b561-4e56-848c-019b323871dd" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_f746b84e-8d00-475f-9592-062742005ebf" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_f746b84e-8d00-475f-9592-062742005ebf_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_f746b84e-8d00-475f-9592-062742005ebf" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_f746b84e-8d00-475f-9592-062742005ebf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_2717b828-103f-42a4-b2ee-5c283ba17d36" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_f746b84e-8d00-475f-9592-062742005ebf" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_2717b828-103f-42a4-b2ee-5c283ba17d36" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_dd02fce0-82c3-45c3-8a72-69dd93fa2536" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_98c8f5f6-b561-4e56-848c-019b323871dd" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_dd02fce0-82c3-45c3-8a72-69dd93fa2536" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_dd02fce0-82c3-45c3-8a72-69dd93fa2536_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_dd02fce0-82c3-45c3-8a72-69dd93fa2536" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_dd02fce0-82c3-45c3-8a72-69dd93fa2536_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_9e2a8cae-8b39-4f52-af55-9db2be683d3f" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_dd02fce0-82c3-45c3-8a72-69dd93fa2536" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_9e2a8cae-8b39-4f52-af55-9db2be683d3f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_536d9e56-d60c-45e1-b076-9bccc904ff5d" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_98c8f5f6-b561-4e56-848c-019b323871dd" xlink:to="loc_srt_RangeAxis_536d9e56-d60c-45e1-b076-9bccc904ff5d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_536d9e56-d60c-45e1-b076-9bccc904ff5d_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_536d9e56-d60c-45e1-b076-9bccc904ff5d" xlink:to="loc_srt_RangeMember_536d9e56-d60c-45e1-b076-9bccc904ff5d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_5543e118-51d0-44f5-ac89-8a2638f82bee" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_536d9e56-d60c-45e1-b076-9bccc904ff5d" xlink:to="loc_srt_RangeMember_5543e118-51d0-44f5-ac89-8a2638f82bee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_ccb655d1-7656-4a2c-86a3-aef8246dcf5b" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_5543e118-51d0-44f5-ac89-8a2638f82bee" xlink:to="loc_srt_MinimumMember_ccb655d1-7656-4a2c-86a3-aef8246dcf5b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_d2e6a90a-cb79-4522-b332-ea7a2860e4bc" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_5543e118-51d0-44f5-ac89-8a2638f82bee" xlink:to="loc_srt_MaximumMember_d2e6a90a-cb79-4522-b332-ea7a2860e4bc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_4001a977-bfe3-4dd7-a4d8-1b76d1e2f055" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_98c8f5f6-b561-4e56-848c-019b323871dd" xlink:to="loc_us-gaap_VariableRateAxis_4001a977-bfe3-4dd7-a4d8-1b76d1e2f055" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_4001a977-bfe3-4dd7-a4d8-1b76d1e2f055_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_4001a977-bfe3-4dd7-a4d8-1b76d1e2f055" xlink:to="loc_us-gaap_VariableRateDomain_4001a977-bfe3-4dd7-a4d8-1b76d1e2f055_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_9ac4bdba-53e2-4821-98fa-a3778006a31f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_4001a977-bfe3-4dd7-a4d8-1b76d1e2f055" xlink:to="loc_us-gaap_VariableRateDomain_9ac4bdba-53e2-4821-98fa-a3778006a31f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BaseRateMember_4e7593e2-83cb-46c9-987b-8e7da3c67197" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BaseRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_9ac4bdba-53e2-4821-98fa-a3778006a31f" xlink:to="loc_us-gaap_BaseRateMember_4e7593e2-83cb-46c9-987b-8e7da3c67197" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_9bacebf0-6067-426e-9353-851443dc162c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_9ac4bdba-53e2-4821-98fa-a3778006a31f" xlink:to="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_9bacebf0-6067-426e-9353-851443dc162c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_82f90615-369b-428a-88e7-91668dd0a912" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_98c8f5f6-b561-4e56-848c-019b323871dd" xlink:to="loc_srt_StatementScenarioAxis_82f90615-369b-428a-88e7-91668dd0a912" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_82f90615-369b-428a-88e7-91668dd0a912_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_82f90615-369b-428a-88e7-91668dd0a912" xlink:to="loc_srt_ScenarioUnspecifiedDomain_82f90615-369b-428a-88e7-91668dd0a912_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_f8bc906d-a58b-44d1-875b-669603101dcf" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_82f90615-369b-428a-88e7-91668dd0a912" xlink:to="loc_srt_ScenarioUnspecifiedDomain_f8bc906d-a58b-44d1-875b-669603101dcf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioForecastMember_bbe68d7c-617d-47bc-a03d-d5bfc9f0c76e" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ScenarioForecastMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ScenarioUnspecifiedDomain_f8bc906d-a58b-44d1-875b-669603101dcf" xlink:to="loc_srt_ScenarioForecastMember_bbe68d7c-617d-47bc-a03d-d5bfc9f0c76e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_aae4fa99-1820-413e-af25-464bec835604" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_98c8f5f6-b561-4e56-848c-019b323871dd" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_aae4fa99-1820-413e-af25-464bec835604" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_aae4fa99-1820-413e-af25-464bec835604_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_aae4fa99-1820-413e-af25-464bec835604" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_aae4fa99-1820-413e-af25-464bec835604_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_e2ed6b4d-ddb9-48f2-bc1c-eae3b8732994" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_aae4fa99-1820-413e-af25-464bec835604" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_e2ed6b4d-ddb9-48f2-bc1c-eae3b8732994" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_8f4f8cef-7204-46fe-8494-55188498a64d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_e2ed6b4d-ddb9-48f2-bc1c-eae3b8732994" xlink:to="loc_us-gaap_SubsequentEventMember_8f4f8cef-7204-46fe-8494-55188498a64d" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/DebtandCreditAgreementsOutstandingAmountsUnderRevolvingCreditFacilityDetails" xlink:type="simple" xlink:href="hsc-20211231.xsd#DebtandCreditAgreementsOutstandingAmountsUnderRevolvingCreditFacilityDetails"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/DebtandCreditAgreementsOutstandingAmountsUnderRevolvingCreditFacilityDetails" xlink:type="extended" id="iec7799590bec4aa0b9f6fc7294d181e9_DebtandCreditAgreementsOutstandingAmountsUnderRevolvingCreditFacilityDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_9987bbbe-a122-4f4a-afa9-30de040f7f8e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_09c98cd1-346b-4c8f-9e97-427328c4a4ca" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9987bbbe-a122-4f4a-afa9-30de040f7f8e" xlink:to="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_09c98cd1-346b-4c8f-9e97-427328c4a4ca" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_d0163ac7-2b21-4800-a4fd-139268b592de" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9987bbbe-a122-4f4a-afa9-30de040f7f8e" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_d0163ac7-2b21-4800-a4fd-139268b592de" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_e8339fba-a6ba-41cb-934d-897a0be3a069" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9987bbbe-a122-4f4a-afa9-30de040f7f8e" xlink:to="loc_us-gaap_LineOfCredit_e8339fba-a6ba-41cb-934d-897a0be3a069" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_958d8666-d4ac-4d9c-8c79-f602cff11f4f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LettersOfCreditOutstandingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9987bbbe-a122-4f4a-afa9-30de040f7f8e" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_958d8666-d4ac-4d9c-8c79-f602cff11f4f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_c42ef3a6-9088-4974-9f76-d62442c4a3ff" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9987bbbe-a122-4f4a-afa9-30de040f7f8e" xlink:to="loc_us-gaap_DebtInstrumentTable_c42ef3a6-9088-4974-9f76-d62442c4a3ff" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_83bca90e-0a8a-4f0f-be73-61b5bc9406f4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_c42ef3a6-9088-4974-9f76-d62442c4a3ff" xlink:to="loc_us-gaap_CreditFacilityAxis_83bca90e-0a8a-4f0f-be73-61b5bc9406f4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_83bca90e-0a8a-4f0f-be73-61b5bc9406f4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_83bca90e-0a8a-4f0f-be73-61b5bc9406f4" xlink:to="loc_us-gaap_CreditFacilityDomain_83bca90e-0a8a-4f0f-be73-61b5bc9406f4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_6a80cf30-68bb-4a64-b41e-76483882db53" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_83bca90e-0a8a-4f0f-be73-61b5bc9406f4" xlink:to="loc_us-gaap_CreditFacilityDomain_6a80cf30-68bb-4a64-b41e-76483882db53" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_8c8dba20-f4dc-477f-8447-0c36a9306b60" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_6a80cf30-68bb-4a64-b41e-76483882db53" xlink:to="loc_us-gaap_LineOfCreditMember_8c8dba20-f4dc-477f-8447-0c36a9306b60" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/LeasesSupplementalCashFlowInformationDetails" xlink:type="simple" xlink:href="hsc-20211231.xsd#LeasesSupplementalCashFlowInformationDetails"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/LeasesSupplementalCashFlowInformationDetails" xlink:type="extended" id="i2d3b19bff8fd4324aaf2b0c06b5db27d_LeasesSupplementalCashFlowInformationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_d6b9fbd1-77e7-4fa7-abf1-4aff09bf8925" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeasePayments_6f3c4ae7-84cb-494b-ae01-ca1dc63f1413" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeasePayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_d6b9fbd1-77e7-4fa7-abf1-4aff09bf8925" xlink:to="loc_us-gaap_OperatingLeasePayments_6f3c4ae7-84cb-494b-ae01-ca1dc63f1413" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseInterestPaymentOnLiability_2305504e-75f6-4459-aa38-27919a71546f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinanceLeaseInterestPaymentOnLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_d6b9fbd1-77e7-4fa7-abf1-4aff09bf8925" xlink:to="loc_us-gaap_FinanceLeaseInterestPaymentOnLiability_2305504e-75f6-4459-aa38-27919a71546f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_3fdf9804-da0c-4c09-89ac-4a7cd42483f5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_d6b9fbd1-77e7-4fa7-abf1-4aff09bf8925" xlink:to="loc_us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_3fdf9804-da0c-4c09-89ac-4a7cd42483f5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability_d633eed1-4d18-42f9-8d1e-f405a79344e3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_d6b9fbd1-77e7-4fa7-abf1-4aff09bf8925" xlink:to="loc_us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability_d633eed1-4d18-42f9-8d1e-f405a79344e3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseRightofUseAsset_19c53f3f-0687-4d8b-a083-22bfa9944a4c" xlink:href="hsc-20211231.xsd#hsc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseRightofUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_d6b9fbd1-77e7-4fa7-abf1-4aff09bf8925" xlink:to="loc_hsc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseRightofUseAsset_19c53f3f-0687-4d8b-a083-22bfa9944a4c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_1ba05293-c558-45b5-a0b5-5ada6063939e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_d6b9fbd1-77e7-4fa7-abf1-4aff09bf8925" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_1ba05293-c558-45b5-a0b5-5ada6063939e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_a061350b-e315-4bd3-9682-ab108391a18c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_1ba05293-c558-45b5-a0b5-5ada6063939e" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_a061350b-e315-4bd3-9682-ab108391a18c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_a061350b-e315-4bd3-9682-ab108391a18c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_a061350b-e315-4bd3-9682-ab108391a18c" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_a061350b-e315-4bd3-9682-ab108391a18c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6b4d0c8b-2079-44d0-a936-5329d39883e6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_a061350b-e315-4bd3-9682-ab108391a18c" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6b4d0c8b-2079-44d0-a936-5329d39883e6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ESOLMember_5ecd4c14-a434-469e-b612-f90dd4b8cfca" xlink:href="hsc-20211231.xsd#hsc_ESOLMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6b4d0c8b-2079-44d0-a936-5329d39883e6" xlink:to="loc_hsc_ESOLMember_5ecd4c14-a434-469e-b612-f90dd4b8cfca" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/EmployeeBenefitPlansTables" xlink:type="simple" xlink:href="hsc-20211231.xsd#EmployeeBenefitPlansTables"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/EmployeeBenefitPlansTables" xlink:type="extended" id="i61fef4bedb22416cad314b418b21548c_EmployeeBenefitPlansTables">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_ac64ccf1-47f6-47b6-a15f-797bc8a321fa" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfNetBenefitCostsTableTextBlock_9f0d8b16-f79f-4bc5-aff1-fecfea4fe2d9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfNetBenefitCostsTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_ac64ccf1-47f6-47b6-a15f-797bc8a321fa" xlink:to="loc_us-gaap_ScheduleOfNetBenefitCostsTableTextBlock_9f0d8b16-f79f-4bc5-aff1-fecfea4fe2d9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfNetFundedStatusTableTextBlock_e6f9dab3-809f-4aa5-8597-e1dc260cab6e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfNetFundedStatusTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_ac64ccf1-47f6-47b6-a15f-797bc8a321fa" xlink:to="loc_us-gaap_ScheduleOfNetFundedStatusTableTextBlock_e6f9dab3-809f-4aa5-8597-e1dc260cab6e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAmountsRecognizedInBalanceSheetTableTextBlock_5a4ad53c-e191-4212-a36f-4f23178dcad0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfAmountsRecognizedInBalanceSheetTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_ac64ccf1-47f6-47b6-a15f-797bc8a321fa" xlink:to="loc_us-gaap_ScheduleOfAmountsRecognizedInBalanceSheetTableTextBlock_5a4ad53c-e191-4212-a36f-4f23178dcad0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfNetPeriodicBenefitCostNotYetRecognizedTableTextBlock_294d9cb4-4153-4692-9b9b-d627a554fbcd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfNetPeriodicBenefitCostNotYetRecognizedTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_ac64ccf1-47f6-47b6-a15f-797bc8a321fa" xlink:to="loc_us-gaap_ScheduleOfNetPeriodicBenefitCostNotYetRecognizedTableTextBlock_294d9cb4-4153-4692-9b9b-d627a554fbcd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfExpectedBenefitPaymentsTableTextBlock_5d37dc67-3b63-4805-a230-5cff63161071" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfExpectedBenefitPaymentsTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_ac64ccf1-47f6-47b6-a15f-797bc8a321fa" xlink:to="loc_us-gaap_ScheduleOfExpectedBenefitPaymentsTableTextBlock_5d37dc67-3b63-4805-a230-5cff63161071" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAssumptionsUsedTableTextBlock_0ea42ae5-9538-4fd8-b228-a0c729f2cdbb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfAssumptionsUsedTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_ac64ccf1-47f6-47b6-a15f-797bc8a321fa" xlink:to="loc_us-gaap_ScheduleOfAssumptionsUsedTableTextBlock_0ea42ae5-9538-4fd8-b228-a0c729f2cdbb" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ScheduleOfAccumulatedBenefitObligationsTableTextBlock_eac3bbf3-2de2-4246-aacc-321931f48841" xlink:href="hsc-20211231.xsd#hsc_ScheduleOfAccumulatedBenefitObligationsTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_ac64ccf1-47f6-47b6-a15f-797bc8a321fa" xlink:to="loc_hsc_ScheduleOfAccumulatedBenefitObligationsTableTextBlock_eac3bbf3-2de2-4246-aacc-321931f48841" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAccumulatedBenefitObligationsInExcessOfFairValueOfPlanAssetsTableTextBlock_c5f3b9d5-e5b7-4d43-8261-7754344e1c50" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfAccumulatedBenefitObligationsInExcessOfFairValueOfPlanAssetsTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_ac64ccf1-47f6-47b6-a15f-797bc8a321fa" xlink:to="loc_us-gaap_ScheduleOfAccumulatedBenefitObligationsInExcessOfFairValueOfPlanAssetsTableTextBlock_c5f3b9d5-e5b7-4d43-8261-7754344e1c50" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAllocationOfPlanAssetsTableTextBlock_7e3bc246-15d4-47e2-a7de-7d207e867115" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfAllocationOfPlanAssetsTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_ac64ccf1-47f6-47b6-a15f-797bc8a321fa" xlink:to="loc_us-gaap_ScheduleOfAllocationOfPlanAssetsTableTextBlock_7e3bc246-15d4-47e2-a7de-7d207e867115" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable_fd1a5227-0dc4-4b7c-b7d7-204aeebf0cd9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_ac64ccf1-47f6-47b6-a15f-797bc8a321fa" xlink:to="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable_fd1a5227-0dc4-4b7c-b7d7-204aeebf0cd9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanSponsorLocationAxis_4a31c810-ba3b-45e3-91d6-fef44690e48b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetirementPlanSponsorLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable_fd1a5227-0dc4-4b7c-b7d7-204aeebf0cd9" xlink:to="loc_us-gaap_RetirementPlanSponsorLocationAxis_4a31c810-ba3b-45e3-91d6-fef44690e48b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanSponsorLocationDomain_4a31c810-ba3b-45e3-91d6-fef44690e48b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetirementPlanSponsorLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanSponsorLocationAxis_4a31c810-ba3b-45e3-91d6-fef44690e48b" xlink:to="loc_us-gaap_RetirementPlanSponsorLocationDomain_4a31c810-ba3b-45e3-91d6-fef44690e48b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanSponsorLocationDomain_56098f0a-0663-497e-ba8e-d56f0f943e45" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetirementPlanSponsorLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanSponsorLocationAxis_4a31c810-ba3b-45e3-91d6-fef44690e48b" xlink:to="loc_us-gaap_RetirementPlanSponsorLocationDomain_56098f0a-0663-497e-ba8e-d56f0f943e45" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_0ef44587-f332-40e0-9ae1-69add100c62d" xlink:href="https://xbrl.sec.gov/country/2021/country-2021.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanSponsorLocationDomain_56098f0a-0663-497e-ba8e-d56f0f943e45" xlink:to="loc_country_US_0ef44587-f332-40e0-9ae1-69add100c62d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignPlanMember_e4295ff5-5291-4f08-af9d-38675a9f5fff" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ForeignPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanSponsorLocationDomain_56098f0a-0663-497e-ba8e-d56f0f943e45" xlink:to="loc_us-gaap_ForeignPlanMember_e4295ff5-5291-4f08-af9d-38675a9f5fff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_40359d61-d5d2-4d6c-be6e-9543e25367fb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable_fd1a5227-0dc4-4b7c-b7d7-204aeebf0cd9" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_40359d61-d5d2-4d6c-be6e-9543e25367fb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_40359d61-d5d2-4d6c-be6e-9543e25367fb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_40359d61-d5d2-4d6c-be6e-9543e25367fb" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_40359d61-d5d2-4d6c-be6e-9543e25367fb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_b1172d4b-c676-46b7-9c1d-4efb70139372" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_40359d61-d5d2-4d6c-be6e-9543e25367fb" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_b1172d4b-c676-46b7-9c1d-4efb70139372" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_857156a8-4a4e-4f11-8540-cb3786bf863a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_b1172d4b-c676-46b7-9c1d-4efb70139372" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_857156a8-4a4e-4f11-8540-cb3786bf863a" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/EmployeeBenefitPlansDetails" xlink:type="simple" xlink:href="hsc-20211231.xsd#EmployeeBenefitPlansDetails"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/EmployeeBenefitPlansDetails" xlink:type="extended" id="i6620dab17a0d4f8fa8152ad8599042e6_EmployeeBenefitPlansDetails">
    <link:loc xlink:type="locator" xlink:label="loc_hsc_PensionAndPostretirementPlansLineItems_cfa26389-4790-4afc-8ca3-5c1111daad22" xlink:href="hsc-20211231.xsd#hsc_PensionAndPostretirementPlansLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DefinedContributionPlanAbstract_56ec6a00-75e9-4c09-be40-b5c1f2397fd3" xlink:href="hsc-20211231.xsd#hsc_DefinedContributionPlanAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hsc_PensionAndPostretirementPlansLineItems_cfa26389-4790-4afc-8ca3-5c1111daad22" xlink:to="loc_hsc_DefinedContributionPlanAbstract_56ec6a00-75e9-4c09-be40-b5c1f2397fd3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent_84209915-c0a1-4008-80fa-0543dfbe0cf2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hsc_DefinedContributionPlanAbstract_56ec6a00-75e9-4c09-be40-b5c1f2397fd3" xlink:to="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent_84209915-c0a1-4008-80fa-0543dfbe0cf2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount_421cdf98-7e6f-4539-ad85-c9accec6e83d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hsc_DefinedContributionPlanAbstract_56ec6a00-75e9-4c09-be40-b5c1f2397fd3" xlink:to="loc_us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount_421cdf98-7e6f-4539-ad85-c9accec6e83d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DefinedContributionPlanInternationalEmployerContributionForInsuranceAndAdministrativeCostsPercentage_2c7be0fc-dc2e-4929-a89a-c52770f365e4" xlink:href="hsc-20211231.xsd#hsc_DefinedContributionPlanInternationalEmployerContributionForInsuranceAndAdministrativeCostsPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hsc_DefinedContributionPlanAbstract_56ec6a00-75e9-4c09-be40-b5c1f2397fd3" xlink:to="loc_hsc_DefinedContributionPlanInternationalEmployerContributionForInsuranceAndAdministrativeCostsPercentage_2c7be0fc-dc2e-4929-a89a-c52770f365e4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_a650ed50-e05e-4716-ad0a-e0b79265def4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hsc_PensionAndPostretirementPlansLineItems_cfa26389-4790-4afc-8ca3-5c1111daad22" xlink:to="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_a650ed50-e05e-4716-ad0a-e0b79265def4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanServiceCost_176d4ff9-f47f-49ae-b2a1-7d0a589f6fa3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanServiceCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_a650ed50-e05e-4716-ad0a-e0b79265def4" xlink:to="loc_us-gaap_DefinedBenefitPlanServiceCost_176d4ff9-f47f-49ae-b2a1-7d0a589f6fa3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanInterestCost_2045123a-e374-4229-8196-85f1fca72356" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanInterestCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_a650ed50-e05e-4716-ad0a-e0b79265def4" xlink:to="loc_us-gaap_DefinedBenefitPlanInterestCost_2045123a-e374-4229-8196-85f1fca72356" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_44945062-b564-4f2c-8fb1-292c8be22fa7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_a650ed50-e05e-4716-ad0a-e0b79265def4" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_44945062-b564-4f2c-8fb1-292c8be22fa7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit_6c0c98b5-6e2f-4286-b786-d71e8013cf3a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_a650ed50-e05e-4716-ad0a-e0b79265def4" xlink:to="loc_us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit_6c0c98b5-6e2f-4286-b786-d71e8013cf3a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses_8387c383-9a00-4b5e-ac4f-b48f4ec311cb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_a650ed50-e05e-4716-ad0a-e0b79265def4" xlink:to="loc_us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses_8387c383-9a00-4b5e-ac4f-b48f4ec311cb" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1_25059de8-4e76-4355-b31f-ce04d2bebfa0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_a650ed50-e05e-4716-ad0a-e0b79265def4" xlink:to="loc_us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1_25059de8-4e76-4355-b31f-ce04d2bebfa0" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_d2257db9-b29f-4452-9b61-6bc2e2ead2e3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hsc_PensionAndPostretirementPlansLineItems_cfa26389-4790-4afc-8ca3-5c1111daad22" xlink:to="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_d2257db9-b29f-4452-9b61-6bc2e2ead2e3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_MultiemployerPlanCostRecognized_9ea9fc26-8839-4cdb-9c52-80b31d780db7" xlink:href="hsc-20211231.xsd#hsc_MultiemployerPlanCostRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hsc_PensionAndPostretirementPlansLineItems_cfa26389-4790-4afc-8ca3-5c1111daad22" xlink:to="loc_hsc_MultiemployerPlanCostRecognized_9ea9fc26-8839-4cdb-9c52-80b31d780db7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanCostRecognized_8e12108a-c3fe-4b66-81b4-5bd9ac93782e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedContributionPlanCostRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hsc_PensionAndPostretirementPlansLineItems_cfa26389-4790-4afc-8ca3-5c1111daad22" xlink:to="loc_us-gaap_DefinedContributionPlanCostRecognized_8e12108a-c3fe-4b66-81b4-5bd9ac93782e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_NetPeriodPensionCostsDomestic_40995259-bf9e-41f4-86d9-a135f2fa5e82" xlink:href="hsc-20211231.xsd#hsc_NetPeriodPensionCostsDomestic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hsc_PensionAndPostretirementPlansLineItems_cfa26389-4790-4afc-8ca3-5c1111daad22" xlink:to="loc_hsc_NetPeriodPensionCostsDomestic_40995259-bf9e-41f4-86d9-a135f2fa5e82" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_NetPeriodPensionCostsForeign_114a66ef-f736-4d2f-bb81-02020244092c" xlink:href="hsc-20211231.xsd#hsc_NetPeriodPensionCostsForeign"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hsc_PensionAndPostretirementPlansLineItems_cfa26389-4790-4afc-8ca3-5c1111daad22" xlink:to="loc_hsc_NetPeriodPensionCostsForeign_114a66ef-f736-4d2f-bb81-02020244092c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ScheduleOfPensionAndPostretirementPlansTable_73e360b3-e4d7-4661-bff1-255bfcdbd3b8" xlink:href="hsc-20211231.xsd#hsc_ScheduleOfPensionAndPostretirementPlansTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_hsc_PensionAndPostretirementPlansLineItems_cfa26389-4790-4afc-8ca3-5c1111daad22" xlink:to="loc_hsc_ScheduleOfPensionAndPostretirementPlansTable_73e360b3-e4d7-4661-bff1-255bfcdbd3b8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanSponsorLocationAxis_e204d3d4-d233-4bea-8690-6e293eff1abb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetirementPlanSponsorLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_hsc_ScheduleOfPensionAndPostretirementPlansTable_73e360b3-e4d7-4661-bff1-255bfcdbd3b8" xlink:to="loc_us-gaap_RetirementPlanSponsorLocationAxis_e204d3d4-d233-4bea-8690-6e293eff1abb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanSponsorLocationDomain_e204d3d4-d233-4bea-8690-6e293eff1abb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetirementPlanSponsorLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanSponsorLocationAxis_e204d3d4-d233-4bea-8690-6e293eff1abb" xlink:to="loc_us-gaap_RetirementPlanSponsorLocationDomain_e204d3d4-d233-4bea-8690-6e293eff1abb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanSponsorLocationDomain_bbe43ed4-f7b9-46e5-ac8a-ce663314ece3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetirementPlanSponsorLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanSponsorLocationAxis_e204d3d4-d233-4bea-8690-6e293eff1abb" xlink:to="loc_us-gaap_RetirementPlanSponsorLocationDomain_bbe43ed4-f7b9-46e5-ac8a-ce663314ece3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_a4404dfe-ffe4-48bd-a731-c2fc4dac0fa8" xlink:href="https://xbrl.sec.gov/country/2021/country-2021.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanSponsorLocationDomain_bbe43ed4-f7b9-46e5-ac8a-ce663314ece3" xlink:to="loc_country_US_a4404dfe-ffe4-48bd-a731-c2fc4dac0fa8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignPlanMember_621f7e72-091d-4e08-a8ed-5b2e5b35ea52" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ForeignPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanSponsorLocationDomain_bbe43ed4-f7b9-46e5-ac8a-ce663314ece3" xlink:to="loc_us-gaap_ForeignPlanMember_621f7e72-091d-4e08-a8ed-5b2e5b35ea52" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_978e2977-b517-4c5d-a89b-7b50f96df69b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_hsc_ScheduleOfPensionAndPostretirementPlansTable_73e360b3-e4d7-4661-bff1-255bfcdbd3b8" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_978e2977-b517-4c5d-a89b-7b50f96df69b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_978e2977-b517-4c5d-a89b-7b50f96df69b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_978e2977-b517-4c5d-a89b-7b50f96df69b" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_978e2977-b517-4c5d-a89b-7b50f96df69b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_94bf758d-54a5-4377-b2e6-439701b7844e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_978e2977-b517-4c5d-a89b-7b50f96df69b" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_94bf758d-54a5-4377-b2e6-439701b7844e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_bd36871e-a0fd-49ee-9248-264a88fa2dd3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_94bf758d-54a5-4377-b2e6-439701b7844e" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_bd36871e-a0fd-49ee-9248-264a88fa2dd3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_ad03b42a-3d7f-4654-9f51-ae8e911f86f2" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_hsc_ScheduleOfPensionAndPostretirementPlansTable_73e360b3-e4d7-4661-bff1-255bfcdbd3b8" xlink:to="loc_srt_RangeAxis_ad03b42a-3d7f-4654-9f51-ae8e911f86f2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_ad03b42a-3d7f-4654-9f51-ae8e911f86f2_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_ad03b42a-3d7f-4654-9f51-ae8e911f86f2" xlink:to="loc_srt_RangeMember_ad03b42a-3d7f-4654-9f51-ae8e911f86f2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_77f0e718-6688-419c-bc52-2718b75924c7" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_ad03b42a-3d7f-4654-9f51-ae8e911f86f2" xlink:to="loc_srt_RangeMember_77f0e718-6688-419c-bc52-2718b75924c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_a3fb5df3-b299-4b3e-ae00-1fec37add4fc" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_77f0e718-6688-419c-bc52-2718b75924c7" xlink:to="loc_srt_MaximumMember_a3fb5df3-b299-4b3e-ae00-1fec37add4fc" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/EmployeeBenefitPlansDetails2" xlink:type="simple" xlink:href="hsc-20211231.xsd#EmployeeBenefitPlansDetails2"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/EmployeeBenefitPlansDetails2" xlink:type="extended" id="id5afed14678749e1b63509c12cab8d1c_EmployeeBenefitPlansDetails2">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_48e2e918-b5c0-433a-93b5-24c9975d1d98" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_ecedac91-ad6d-45c5-9a4a-dfbf77515989" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_48e2e918-b5c0-433a-93b5-24c9975d1d98" xlink:to="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_ecedac91-ad6d-45c5-9a4a-dfbf77515989" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligation_2b7f40bd-7507-4e81-bcf4-5518246e3ad4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanBenefitObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_ecedac91-ad6d-45c5-9a4a-dfbf77515989" xlink:to="loc_us-gaap_DefinedBenefitPlanBenefitObligation_2b7f40bd-7507-4e81-bcf4-5518246e3ad4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanServiceCost_bded719e-2bcc-43dd-8c67-f9fe3ab425b1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanServiceCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_ecedac91-ad6d-45c5-9a4a-dfbf77515989" xlink:to="loc_us-gaap_DefinedBenefitPlanServiceCost_bded719e-2bcc-43dd-8c67-f9fe3ab425b1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanInterestCost_fb62e297-5c03-4b9d-b32b-3b111e557a99" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanInterestCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_ecedac91-ad6d-45c5-9a4a-dfbf77515989" xlink:to="loc_us-gaap_DefinedBenefitPlanInterestCost_fb62e297-5c03-4b9d-b32b-3b111e557a99" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligationContributionsByPlanParticipant_8b227d3d-1f9b-47d4-acdd-72667033cde5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanBenefitObligationContributionsByPlanParticipant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_ecedac91-ad6d-45c5-9a4a-dfbf77515989" xlink:to="loc_us-gaap_DefinedBenefitPlanBenefitObligationContributionsByPlanParticipant_8b227d3d-1f9b-47d4-acdd-72667033cde5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanPlanAmendments_63e977e1-dcf7-4704-a3e4-9c762972f723" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanPlanAmendments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_ecedac91-ad6d-45c5-9a4a-dfbf77515989" xlink:to="loc_us-gaap_DefinedBenefitPlanPlanAmendments_63e977e1-dcf7-4704-a3e4-9c762972f723" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanActuarialGainLoss_74e59942-861f-44dd-8eeb-7bab8f8b9370" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanActuarialGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_ecedac91-ad6d-45c5-9a4a-dfbf77515989" xlink:to="loc_us-gaap_DefinedBenefitPlanActuarialGainLoss_74e59942-861f-44dd-8eeb-7bab8f8b9370" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DefinedBenefitPlanSettlementsAndCurtailmentsBenefitObligation_bedee253-fab8-436c-a29b-a70d0f08e1b0" xlink:href="hsc-20211231.xsd#hsc_DefinedBenefitPlanSettlementsAndCurtailmentsBenefitObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_ecedac91-ad6d-45c5-9a4a-dfbf77515989" xlink:to="loc_hsc_DefinedBenefitPlanSettlementsAndCurtailmentsBenefitObligation_bedee253-fab8-436c-a29b-a70d0f08e1b0" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid_6fa15a74-dbf0-43e0-ab76-5dd5072e1563" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_ecedac91-ad6d-45c5-9a4a-dfbf77515989" xlink:to="loc_us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid_6fa15a74-dbf0-43e0-ab76-5dd5072e1563" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation_3181b1c8-ef38-47de-a700-af7242492bdd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_ecedac91-ad6d-45c5-9a4a-dfbf77515989" xlink:to="loc_us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation_3181b1c8-ef38-47de-a700-af7242492bdd" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ChangeinbenefitobligationAcquisition_f350ebdf-fb91-4443-b6b8-3d16f15c8735" xlink:href="hsc-20211231.xsd#hsc_ChangeinbenefitobligationAcquisition"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_ecedac91-ad6d-45c5-9a4a-dfbf77515989" xlink:to="loc_hsc_ChangeinbenefitobligationAcquisition_f350ebdf-fb91-4443-b6b8-3d16f15c8735" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligation_ad4e1a99-ae22-4602-9dcc-743a5a5805dc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanBenefitObligation"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_3421f48c-4f23-4ab2-ba2d-d376130632bb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_48e2e918-b5c0-433a-93b5-24c9975d1d98" xlink:to="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_3421f48c-4f23-4ab2-ba2d-d376130632bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_6d0de84d-5593-4afc-b7ff-6b84d7397b3c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanFairValueOfPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_3421f48c-4f23-4ab2-ba2d-d376130632bb" xlink:to="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_6d0de84d-5593-4afc-b7ff-6b84d7397b3c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets_4f80d0b1-2c00-4170-9bd1-0b5bb1d173ae" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_3421f48c-4f23-4ab2-ba2d-d376130632bb" xlink:to="loc_us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets_4f80d0b1-2c00-4170-9bd1-0b5bb1d173ae" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_9c7799b8-de6d-4f47-a9ce-3868c0ecbc18" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanContributionsByEmployer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_3421f48c-4f23-4ab2-ba2d-d376130632bb" xlink:to="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_9c7799b8-de6d-4f47-a9ce-3868c0ecbc18" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanPlanAssetsContributionsByPlanParticipant_ebb9c103-bad1-41fc-b39f-9e2885aed0f6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanPlanAssetsContributionsByPlanParticipant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_3421f48c-4f23-4ab2-ba2d-d376130632bb" xlink:to="loc_us-gaap_DefinedBenefitPlanPlanAssetsContributionsByPlanParticipant_ebb9c103-bad1-41fc-b39f-9e2885aed0f6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DefinedBenefitPlanSettlementsAndCurtailmentsPlanAssets_3349152e-c286-4b2a-97dd-ecaa8006c8c6" xlink:href="hsc-20211231.xsd#hsc_DefinedBenefitPlanSettlementsAndCurtailmentsPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_3421f48c-4f23-4ab2-ba2d-d376130632bb" xlink:to="loc_hsc_DefinedBenefitPlanSettlementsAndCurtailmentsPlanAssets_3349152e-c286-4b2a-97dd-ecaa8006c8c6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid_65869d5f-0700-4709-80db-f68db303eec0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_3421f48c-4f23-4ab2-ba2d-d376130632bb" xlink:to="loc_us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid_65869d5f-0700-4709-80db-f68db303eec0" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanPlanAssetsForeignCurrencyTranslationGainLoss_e18bb7fd-3a63-4f4b-8965-5bba01e3e8b9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanPlanAssetsForeignCurrencyTranslationGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_3421f48c-4f23-4ab2-ba2d-d376130632bb" xlink:to="loc_us-gaap_DefinedBenefitPlanPlanAssetsForeignCurrencyTranslationGainLoss_e18bb7fd-3a63-4f4b-8965-5bba01e3e8b9" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DefinedBenefitPlanPlanAssetsBusinessCombinationAndDivestiture_db7f099b-6b80-4dbe-9ab7-3d1dedaf6e7b" xlink:href="hsc-20211231.xsd#hsc_DefinedBenefitPlanPlanAssetsBusinessCombinationAndDivestiture"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_3421f48c-4f23-4ab2-ba2d-d376130632bb" xlink:to="loc_hsc_DefinedBenefitPlanPlanAssetsBusinessCombinationAndDivestiture_db7f099b-6b80-4dbe-9ab7-3d1dedaf6e7b" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_0e491bac-a335-4b39-954b-d12888540d9b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanFairValueOfPlanAssets"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanFundedStatusOfPlan_4e6a4ef6-85f5-48b8-ba1d-a74af6ffa474" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanFundedStatusOfPlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_3421f48c-4f23-4ab2-ba2d-d376130632bb" xlink:to="loc_us-gaap_DefinedBenefitPlanFundedStatusOfPlan_4e6a4ef6-85f5-48b8-ba1d-a74af6ffa474" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheetAbstract_55133165-0c29-47e8-bb07-ea5cb7a33a13" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_48e2e918-b5c0-433a-93b5-24c9975d1d98" xlink:to="loc_us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheetAbstract_55133165-0c29-47e8-bb07-ea5cb7a33a13" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent_c41eeb16-4280-4127-b9ad-c98145199175" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheetAbstract_55133165-0c29-47e8-bb07-ea5cb7a33a13" xlink:to="loc_us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent_c41eeb16-4280-4127-b9ad-c98145199175" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansCurrentLiabilities_a2a7303b-e118-4bc0-ab34-9e5c6744e1fd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansCurrentLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheetAbstract_55133165-0c29-47e8-bb07-ea5cb7a33a13" xlink:to="loc_us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansCurrentLiabilities_a2a7303b-e118-4bc0-ab34-9e5c6744e1fd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent_300bd01e-cd25-4865-a245-5b4c278cd015" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheetAbstract_55133165-0c29-47e8-bb07-ea5cb7a33a13" xlink:to="loc_us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent_300bd01e-cd25-4865-a245-5b4c278cd015" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationNoncurrent_61ebab8b-291d-4ce2-ad9d-c3305b981358" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheetAbstract_55133165-0c29-47e8-bb07-ea5cb7a33a13" xlink:to="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationNoncurrent_61ebab8b-291d-4ce2-ad9d-c3305b981358" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax_bb086e02-6231-4b15-b0ae-2c20bbe1d25c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheetAbstract_55133165-0c29-47e8-bb07-ea5cb7a33a13" xlink:to="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax_bb086e02-6231-4b15-b0ae-2c20bbe1d25c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTaxAbstract_3026575f-0545-4f38-a9dd-317c3854f7d7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTaxAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_48e2e918-b5c0-433a-93b5-24c9975d1d98" xlink:to="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTaxAbstract_3026575f-0545-4f38-a9dd-317c3854f7d7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax_cf4a77ef-f713-4a56-9c99-6e011d4a86cd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTaxAbstract_3026575f-0545-4f38-a9dd-317c3854f7d7" xlink:to="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax_cf4a77ef-f713-4a56-9c99-6e011d4a86cd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax_3ee086cf-4680-4a88-9ac9-af58b7cbb5f0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTaxAbstract_3026575f-0545-4f38-a9dd-317c3854f7d7" xlink:to="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax_3ee086cf-4680-4a88-9ac9-af58b7cbb5f0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax_1360cad3-d022-461d-b88f-4491291f3c5b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAmountsThatWillBeAmortizedFromAccumulatedOtherComprehensiveIncomeLossInNextFiscalYearAbstract_72d4f64d-662f-49f7-aee1-8b184eeb5a70" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanAmountsThatWillBeAmortizedFromAccumulatedOtherComprehensiveIncomeLossInNextFiscalYearAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_48e2e918-b5c0-433a-93b5-24c9975d1d98" xlink:to="loc_us-gaap_DefinedBenefitPlanAmountsThatWillBeAmortizedFromAccumulatedOtherComprehensiveIncomeLossInNextFiscalYearAbstract_72d4f64d-662f-49f7-aee1-8b184eeb5a70" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureEmployerContributionsRemainderOfFiscalYear_d029d603-deaa-4a7f-a3ec-e7759caa0969" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedFutureEmployerContributionsRemainderOfFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanAmountsThatWillBeAmortizedFromAccumulatedOtherComprehensiveIncomeLossInNextFiscalYearAbstract_72d4f64d-662f-49f7-aee1-8b184eeb5a70" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureEmployerContributionsRemainderOfFiscalYear_d029d603-deaa-4a7f-a3ec-e7759caa0969" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract_a05de30c-eba8-467a-8c36-fa2e50f524c6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_48e2e918-b5c0-433a-93b5-24c9975d1d98" xlink:to="loc_us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract_a05de30c-eba8-467a-8c36-fa2e50f524c6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths_81b99fdb-5e31-4a73-b176-a664a1f25e37" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract_a05de30c-eba8-467a-8c36-fa2e50f524c6" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths_81b99fdb-5e31-4a73-b176-a664a1f25e37" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo_e701e654-eb40-44d9-84e9-c774e76cd580" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract_a05de30c-eba8-467a-8c36-fa2e50f524c6" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo_e701e654-eb40-44d9-84e9-c774e76cd580" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree_cf7e68fb-f1c3-413f-a32c-34af3661948a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract_a05de30c-eba8-467a-8c36-fa2e50f524c6" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree_cf7e68fb-f1c3-413f-a32c-34af3661948a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour_e489a580-5817-442b-9cd9-5886042f1757" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract_a05de30c-eba8-467a-8c36-fa2e50f524c6" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour_e489a580-5817-442b-9cd9-5886042f1757" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive_0182af34-91dd-439f-a4e4-2d4e4aabdba3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract_a05de30c-eba8-467a-8c36-fa2e50f524c6" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive_0182af34-91dd-439f-a4e4-2d4e4aabdba3" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter_6675bd60-62dc-4a53-94fa-72f871228b45" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanEstimatedFutureBenefitPaymentsAbstract_a05de30c-eba8-467a-8c36-fa2e50f524c6" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter_6675bd60-62dc-4a53-94fa-72f871228b45" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract_5d5f62ce-ac54-4e93-9508-417a597d8c10" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_48e2e918-b5c0-433a-93b5-24c9975d1d98" xlink:to="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract_5d5f62ce-ac54-4e93-9508-417a597d8c10" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate_6c71f610-5dcd-4c73-921d-8f0cec6bc520" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract_5d5f62ce-ac54-4e93-9508-417a597d8c10" xlink:to="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate_6c71f610-5dcd-4c73-921d-8f0cec6bc520" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets_b1abd06d-02e8-4974-98c8-b17a37004aa7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract_5d5f62ce-ac54-4e93-9508-417a597d8c10" xlink:to="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets_b1abd06d-02e8-4974-98c8-b17a37004aa7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssetsForNextFiscalYear_d2262325-9b8f-4d55-8ca2-29dda9822f82" xlink:href="hsc-20211231.xsd#hsc_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssetsForNextFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingNetPeriodicBenefitCostAbstract_5d5f62ce-ac54-4e93-9508-417a597d8c10" xlink:to="loc_hsc_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssetsForNextFiscalYear_d2262325-9b8f-4d55-8ca2-29dda9822f82" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract_7dc9bc67-6cbf-44ba-980d-03dbb261d8ee" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_48e2e918-b5c0-433a-93b5-24c9975d1d98" xlink:to="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract_7dc9bc67-6cbf-44ba-980d-03dbb261d8ee" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate_1d89d33a-1667-4101-83c3-cb665296e006" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract_7dc9bc67-6cbf-44ba-980d-03dbb261d8ee" xlink:to="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate_1d89d33a-1667-4101-83c3-cb665296e006" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DefinedBenefitPlanAssumptionsUsedInCalculatingBenefitObligationDiscountRatePercentOfHighestYieldAaCorporateBondsExcluded_ebd05a1a-66bb-4104-809f-8151af8f3b27" xlink:href="hsc-20211231.xsd#hsc_DefinedBenefitPlanAssumptionsUsedInCalculatingBenefitObligationDiscountRatePercentOfHighestYieldAaCorporateBondsExcluded"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract_7dc9bc67-6cbf-44ba-980d-03dbb261d8ee" xlink:to="loc_hsc_DefinedBenefitPlanAssumptionsUsedInCalculatingBenefitObligationDiscountRatePercentOfHighestYieldAaCorporateBondsExcluded_ebd05a1a-66bb-4104-809f-8151af8f3b27" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DefinedBenefitPlanAssumptionsUsedInCalculatingBenefitObligationDiscountRatePercentOfLowestYieldAaCorporateBondsExcluded_79b9fb3b-eccb-48b8-8768-a3058b9258c0" xlink:href="hsc-20211231.xsd#hsc_DefinedBenefitPlanAssumptionsUsedInCalculatingBenefitObligationDiscountRatePercentOfLowestYieldAaCorporateBondsExcluded"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssumptionsUsedInCalculatingBenefitObligationAbstract_7dc9bc67-6cbf-44ba-980d-03dbb261d8ee" xlink:to="loc_hsc_DefinedBenefitPlanAssumptionsUsedInCalculatingBenefitObligationDiscountRatePercentOfLowestYieldAaCorporateBondsExcluded_79b9fb3b-eccb-48b8-8768-a3058b9258c0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_7059ce4e-4db8-4fd2-bc20-f03ccbb8b299" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_48e2e918-b5c0-433a-93b5-24c9975d1d98" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_7059ce4e-4db8-4fd2-bc20-f03ccbb8b299" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanSponsorLocationAxis_5bf788fb-ef0a-44af-a087-632895834197" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetirementPlanSponsorLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_7059ce4e-4db8-4fd2-bc20-f03ccbb8b299" xlink:to="loc_us-gaap_RetirementPlanSponsorLocationAxis_5bf788fb-ef0a-44af-a087-632895834197" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanSponsorLocationDomain_5bf788fb-ef0a-44af-a087-632895834197_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetirementPlanSponsorLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanSponsorLocationAxis_5bf788fb-ef0a-44af-a087-632895834197" xlink:to="loc_us-gaap_RetirementPlanSponsorLocationDomain_5bf788fb-ef0a-44af-a087-632895834197_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanSponsorLocationDomain_40b4f376-2b09-4c7b-bfe2-f154fc4b419b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetirementPlanSponsorLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanSponsorLocationAxis_5bf788fb-ef0a-44af-a087-632895834197" xlink:to="loc_us-gaap_RetirementPlanSponsorLocationDomain_40b4f376-2b09-4c7b-bfe2-f154fc4b419b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_6a623e2e-977c-4c1b-a815-21b1aae7cded" xlink:href="https://xbrl.sec.gov/country/2021/country-2021.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanSponsorLocationDomain_40b4f376-2b09-4c7b-bfe2-f154fc4b419b" xlink:to="loc_country_US_6a623e2e-977c-4c1b-a815-21b1aae7cded" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignPlanMember_169e5dde-f330-4ed2-9610-60d0f0e222b5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ForeignPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanSponsorLocationDomain_40b4f376-2b09-4c7b-bfe2-f154fc4b419b" xlink:to="loc_us-gaap_ForeignPlanMember_169e5dde-f330-4ed2-9610-60d0f0e222b5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_f0687715-3a7c-4119-b7b9-e46bc5c4acef" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_7059ce4e-4db8-4fd2-bc20-f03ccbb8b299" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_f0687715-3a7c-4119-b7b9-e46bc5c4acef" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_f0687715-3a7c-4119-b7b9-e46bc5c4acef_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_f0687715-3a7c-4119-b7b9-e46bc5c4acef" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_f0687715-3a7c-4119-b7b9-e46bc5c4acef_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_18efe910-6464-4561-a1b0-fd6108e3f22a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_f0687715-3a7c-4119-b7b9-e46bc5c4acef" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_18efe910-6464-4561-a1b0-fd6108e3f22a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_7d264ea5-99ab-4ce4-ba56-aef1a4ba718b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_18efe910-6464-4561-a1b0-fd6108e3f22a" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_7d264ea5-99ab-4ce4-ba56-aef1a4ba718b" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/EmployeeBenefitPlansDetails3" xlink:type="simple" xlink:href="hsc-20211231.xsd#EmployeeBenefitPlansDetails3"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/EmployeeBenefitPlansDetails3" xlink:type="extended" id="id73bfa271e264df58bf89ce85089911c_EmployeeBenefitPlansDetails3">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_026368e0-26ec-4523-b309-649ed2635db8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAccumulatedBenefitObligation_cf53293a-46ac-4e55-9389-f9fe5b091298" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanAccumulatedBenefitObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_026368e0-26ec-4523-b309-649ed2635db8" xlink:to="loc_us-gaap_DefinedBenefitPlanAccumulatedBenefitObligation_cf53293a-46ac-4e55-9389-f9fe5b091298" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAbstract_2ba4d36c-3272-4f47-9a2e-c5c7ad7b3b48" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_026368e0-26ec-4523-b309-649ed2635db8" xlink:to="loc_us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAbstract_2ba4d36c-3272-4f47-9a2e-c5c7ad7b3b48" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateProjectedBenefitObligation_cbc60123-63cf-4050-b40a-272a558ab9f3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateProjectedBenefitObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAbstract_2ba4d36c-3272-4f47-9a2e-c5c7ad7b3b48" xlink:to="loc_us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateProjectedBenefitObligation_cbc60123-63cf-4050-b40a-272a558ab9f3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateAccumulatedBenefitObligation_f5ac4888-bedc-4f53-a104-ed84af999a74" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateAccumulatedBenefitObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAbstract_2ba4d36c-3272-4f47-9a2e-c5c7ad7b3b48" xlink:to="loc_us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateAccumulatedBenefitObligation_f5ac4888-bedc-4f53-a104-ed84af999a74" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateFairValueOfPlanAssets_2ceeca19-7e3b-4e9d-ada7-34894684b81c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateFairValueOfPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAbstract_2ba4d36c-3272-4f47-9a2e-c5c7ad7b3b48" xlink:to="loc_us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateFairValueOfPlanAssets_2ceeca19-7e3b-4e9d-ada7-34894684b81c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanInformationAboutPlanAssetsAbstract_6f85a52e-6209-4871-9f1f-80c028255c28" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanInformationAboutPlanAssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAbstract_2ba4d36c-3272-4f47-9a2e-c5c7ad7b3b48" xlink:to="loc_us-gaap_DefinedBenefitPlanInformationAboutPlanAssetsAbstract_6f85a52e-6209-4871-9f1f-80c028255c28" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations_1e6d36c9-f8e3-40e3-8f01-0eb39127f800" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanInformationAboutPlanAssetsAbstract_6f85a52e-6209-4871-9f1f-80c028255c28" xlink:to="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations_1e6d36c9-f8e3-40e3-8f01-0eb39127f800" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssetsTargetAllocationsAbstract_8f2b1f2c-d556-43e3-a534-080b2ea0629e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanAssetsTargetAllocationsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanInformationAboutPlanAssetsAbstract_6f85a52e-6209-4871-9f1f-80c028255c28" xlink:to="loc_us-gaap_DefinedBenefitPlanAssetsTargetAllocationsAbstract_8f2b1f2c-d556-43e3-a534-080b2ea0629e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanPlanAssetsTargetAllocationPercentage_d6dd36ee-b92f-4935-8242-802b4d2e2b93" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanPlanAssetsTargetAllocationPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanAssetsTargetAllocationsAbstract_8f2b1f2c-d556-43e3-a534-080b2ea0629e" xlink:to="loc_us-gaap_DefinedBenefitPlanPlanAssetsTargetAllocationPercentage_d6dd36ee-b92f-4935-8242-802b4d2e2b93" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DefinedBenefitPlanExpectedLongTermReturnOnPlanAssetsNumberOfCapitalMarketResultsSimulated_dec341b2-1f8b-4c1a-a8ab-3ac7b77f719f" xlink:href="hsc-20211231.xsd#hsc_DefinedBenefitPlanExpectedLongTermReturnOnPlanAssetsNumberOfCapitalMarketResultsSimulated"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_026368e0-26ec-4523-b309-649ed2635db8" xlink:to="loc_hsc_DefinedBenefitPlanExpectedLongTermReturnOnPlanAssetsNumberOfCapitalMarketResultsSimulated_dec341b2-1f8b-4c1a-a8ab-3ac7b77f719f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DefinedBenefitPlanExpectedLongTermReturnOnPlanAssetsPeriodForWhichResultsOfCapitalMarketsSimulated_95867fd3-1d06-460d-ab2c-7d9a05886874" xlink:href="hsc-20211231.xsd#hsc_DefinedBenefitPlanExpectedLongTermReturnOnPlanAssetsPeriodForWhichResultsOfCapitalMarketsSimulated"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_026368e0-26ec-4523-b309-649ed2635db8" xlink:to="loc_hsc_DefinedBenefitPlanExpectedLongTermReturnOnPlanAssetsPeriodForWhichResultsOfCapitalMarketsSimulated_95867fd3-1d06-460d-ab2c-7d9a05886874" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssetsForNextFiscalYear_3bc496d3-1007-4db7-9cb5-d3412981e071" xlink:href="hsc-20211231.xsd#hsc_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssetsForNextFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_026368e0-26ec-4523-b309-649ed2635db8" xlink:to="loc_hsc_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssetsForNextFiscalYear_3bc496d3-1007-4db7-9cb5-d3412981e071" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets_a29b1c9f-3815-4d34-8c8b-22f08976b5f3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_026368e0-26ec-4523-b309-649ed2635db8" xlink:to="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets_a29b1c9f-3815-4d34-8c8b-22f08976b5f3" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanNumberOfSharesOfEquitySecuritiesIssuedByEmployerAndRelatedPartiesIncludedInPlanAssets_27ab848b-0deb-45e6-81d6-da59c02ed94c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanNumberOfSharesOfEquitySecuritiesIssuedByEmployerAndRelatedPartiesIncludedInPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_026368e0-26ec-4523-b309-649ed2635db8" xlink:to="loc_us-gaap_DefinedBenefitPlanNumberOfSharesOfEquitySecuritiesIssuedByEmployerAndRelatedPartiesIncludedInPlanAssets_27ab848b-0deb-45e6-81d6-da59c02ed94c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAmountOfEmployerAndRelatedPartySecuritiesIncludedInPlanAssets_874059ce-4d23-49c1-a063-222c157f2169" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanAmountOfEmployerAndRelatedPartySecuritiesIncludedInPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_026368e0-26ec-4523-b309-649ed2635db8" xlink:to="loc_us-gaap_DefinedBenefitPlanAmountOfEmployerAndRelatedPartySecuritiesIncludedInPlanAssets_874059ce-4d23-49c1-a063-222c157f2169" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DefinedBenefitPlanAssetsAsPercentageOfForeignPlanAssets_a78701ba-47a5-41a3-9c5f-ed24ebb43c63" xlink:href="hsc-20211231.xsd#hsc_DefinedBenefitPlanAssetsAsPercentageOfForeignPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_026368e0-26ec-4523-b309-649ed2635db8" xlink:to="loc_hsc_DefinedBenefitPlanAssetsAsPercentageOfForeignPlanAssets_a78701ba-47a5-41a3-9c5f-ed24ebb43c63" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_71920dbb-2256-49de-877f-2a4bd3b7917e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanFairValueOfPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_026368e0-26ec-4523-b309-649ed2635db8" xlink:to="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_71920dbb-2256-49de-877f-2a4bd3b7917e" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_bb55164d-75b2-4715-b78e-3361b45c0874" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_026368e0-26ec-4523-b309-649ed2635db8" xlink:to="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_bb55164d-75b2-4715-b78e-3361b45c0874" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_5e993821-e2f9-4b32-b54e-a5e26a5ae1cf" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanFairValueOfPlanAssets"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_ec3a2444-be63-44f1-a583-6cf3bcae9dd4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanContributionsByEmployer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_bb55164d-75b2-4715-b78e-3361b45c0874" xlink:to="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_ec3a2444-be63-44f1-a583-6cf3bcae9dd4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_8fb82403-d626-420c-ae24-bcff35810b84" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanFairValueOfPlanAssets"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_475c64d9-0bbe-4c75-873e-1982efb87c19" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_026368e0-26ec-4523-b309-649ed2635db8" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_475c64d9-0bbe-4c75-873e-1982efb87c19" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanSponsorLocationAxis_7411d1c7-12f4-4184-ade0-81b3ebcc57aa" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetirementPlanSponsorLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_475c64d9-0bbe-4c75-873e-1982efb87c19" xlink:to="loc_us-gaap_RetirementPlanSponsorLocationAxis_7411d1c7-12f4-4184-ade0-81b3ebcc57aa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanSponsorLocationDomain_7411d1c7-12f4-4184-ade0-81b3ebcc57aa_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetirementPlanSponsorLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanSponsorLocationAxis_7411d1c7-12f4-4184-ade0-81b3ebcc57aa" xlink:to="loc_us-gaap_RetirementPlanSponsorLocationDomain_7411d1c7-12f4-4184-ade0-81b3ebcc57aa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanSponsorLocationDomain_1b0ce083-69e2-4c21-80f7-45b79272795e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetirementPlanSponsorLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanSponsorLocationAxis_7411d1c7-12f4-4184-ade0-81b3ebcc57aa" xlink:to="loc_us-gaap_RetirementPlanSponsorLocationDomain_1b0ce083-69e2-4c21-80f7-45b79272795e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_InternationalOtherThanUnitedKingdomMember_470b16bc-0817-478a-948f-23d7cb7e5155" xlink:href="hsc-20211231.xsd#hsc_InternationalOtherThanUnitedKingdomMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanSponsorLocationDomain_1b0ce083-69e2-4c21-80f7-45b79272795e" xlink:to="loc_hsc_InternationalOtherThanUnitedKingdomMember_470b16bc-0817-478a-948f-23d7cb7e5155" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_fad20c57-b004-4dbf-a99f-b24a991ebcce" xlink:href="https://xbrl.sec.gov/country/2021/country-2021.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanSponsorLocationDomain_1b0ce083-69e2-4c21-80f7-45b79272795e" xlink:to="loc_country_US_fad20c57-b004-4dbf-a99f-b24a991ebcce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignPlanMember_aaa36aa5-79b0-436f-9e15-00b206e1f10b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ForeignPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanSponsorLocationDomain_1b0ce083-69e2-4c21-80f7-45b79272795e" xlink:to="loc_us-gaap_ForeignPlanMember_aaa36aa5-79b0-436f-9e15-00b206e1f10b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_GB_5fdd5e30-0189-4b9b-8336-1cb1650222b8" xlink:href="https://xbrl.sec.gov/country/2021/country-2021.xsd#country_GB"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanSponsorLocationDomain_1b0ce083-69e2-4c21-80f7-45b79272795e" xlink:to="loc_country_GB_5fdd5e30-0189-4b9b-8336-1cb1650222b8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_e2207868-0e0e-4c5d-bddb-e468c5e842d8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_475c64d9-0bbe-4c75-873e-1982efb87c19" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_e2207868-0e0e-4c5d-bddb-e468c5e842d8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_e2207868-0e0e-4c5d-bddb-e468c5e842d8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_e2207868-0e0e-4c5d-bddb-e468c5e842d8" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_e2207868-0e0e-4c5d-bddb-e468c5e842d8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_072352d3-b419-4466-a871-89ba4726ca8b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_e2207868-0e0e-4c5d-bddb-e468c5e842d8" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_072352d3-b419-4466-a871-89ba4726ca8b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_47d6f7b6-78e7-4201-a764-ccfcb98860a7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_072352d3-b419-4466-a871-89ba4726ca8b" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_47d6f7b6-78e7-4201-a764-ccfcb98860a7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_7d2f792f-db59-42c9-8661-1892a820a356" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_475c64d9-0bbe-4c75-873e-1982efb87c19" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_7d2f792f-db59-42c9-8661-1892a820a356" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7d2f792f-db59-42c9-8661-1892a820a356_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_7d2f792f-db59-42c9-8661-1892a820a356" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7d2f792f-db59-42c9-8661-1892a820a356_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_b96eb7b8-b409-44ed-a4c9-3343c39f1de0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_7d2f792f-db59-42c9-8661-1892a820a356" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_b96eb7b8-b409-44ed-a4c9-3343c39f1de0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_ab404a2b-50f2-4577-a171-b6bca741e5d7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_b96eb7b8-b409-44ed-a4c9-3343c39f1de0" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_ab404a2b-50f2-4577-a171-b6bca741e5d7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember_64551204-570d-4ded-8a9b-fbabe59218a6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_b96eb7b8-b409-44ed-a4c9-3343c39f1de0" xlink:to="loc_us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember_64551204-570d-4ded-8a9b-fbabe59218a6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_67c57d69-4371-44e6-9853-b334e18eb004" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_b96eb7b8-b409-44ed-a4c9-3343c39f1de0" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_67c57d69-4371-44e6-9853-b334e18eb004" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_da7fdfee-2626-4e78-8e37-e95b3444e64b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_475c64d9-0bbe-4c75-873e-1982efb87c19" xlink:to="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_da7fdfee-2626-4e78-8e37-e95b3444e64b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanAssetCategoriesDomain_da7fdfee-2626-4e78-8e37-e95b3444e64b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanAssetCategoriesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_da7fdfee-2626-4e78-8e37-e95b3444e64b" xlink:to="loc_us-gaap_PlanAssetCategoriesDomain_da7fdfee-2626-4e78-8e37-e95b3444e64b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanAssetCategoriesDomain_98cecd30-dd82-4c2b-bef5-90cb7ca5668a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanAssetCategoriesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_da7fdfee-2626-4e78-8e37-e95b3444e64b" xlink:to="loc_us-gaap_PlanAssetCategoriesDomain_98cecd30-dd82-4c2b-bef5-90cb7ca5668a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesMember_9bbb3014-e572-4d95-9f06-0732f3aca042" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquitySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_98cecd30-dd82-4c2b-bef5-90cb7ca5668a" xlink:to="loc_us-gaap_EquitySecuritiesMember_9bbb3014-e572-4d95-9f06-0732f3aca042" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_EquitySecuritiesDomesticMember_fcf13fb6-37a6-409a-9fdc-d5372f67e7d5" xlink:href="hsc-20211231.xsd#hsc_EquitySecuritiesDomesticMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_98cecd30-dd82-4c2b-bef5-90cb7ca5668a" xlink:to="loc_hsc_EquitySecuritiesDomesticMember_fcf13fb6-37a6-409a-9fdc-d5372f67e7d5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_EquityFundsDomesticMember_3ae6bc0b-3c5f-4d3a-ba15-270e373a96ce" xlink:href="hsc-20211231.xsd#hsc_EquityFundsDomesticMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_98cecd30-dd82-4c2b-bef5-90cb7ca5668a" xlink:to="loc_hsc_EquityFundsDomesticMember_3ae6bc0b-3c5f-4d3a-ba15-270e373a96ce" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_EquitySecuritiesInternationalMember_10b03935-ce53-4cb5-a5b8-0a5cbe734079" xlink:href="hsc-20211231.xsd#hsc_EquitySecuritiesInternationalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_98cecd30-dd82-4c2b-bef5-90cb7ca5668a" xlink:to="loc_hsc_EquitySecuritiesInternationalMember_10b03935-ce53-4cb5-a5b8-0a5cbe734079" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_EquityFundsInternationalMember_de146c17-a4e7-4991-8985-f7fee1a9d040" xlink:href="hsc-20211231.xsd#hsc_EquityFundsInternationalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_98cecd30-dd82-4c2b-bef5-90cb7ca5668a" xlink:to="loc_hsc_EquityFundsInternationalMember_de146c17-a4e7-4991-8985-f7fee1a9d040" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_CompanysOwnCommonStockMember_8847cb91-86ea-4a60-af73-a84b5e52eb86" xlink:href="hsc-20211231.xsd#hsc_CompanysOwnCommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_98cecd30-dd82-4c2b-bef5-90cb7ca5668a" xlink:to="loc_hsc_CompanysOwnCommonStockMember_8847cb91-86ea-4a60-af73-a84b5e52eb86" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityFundsMember_4622ffa9-b73d-4adb-9e88-9bf0fbff4131" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityFundsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_98cecd30-dd82-4c2b-bef5-90cb7ca5668a" xlink:to="loc_us-gaap_EquityFundsMember_4622ffa9-b73d-4adb-9e88-9bf0fbff4131" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesMember_40e4020d-d8f4-4efa-8cfb-9635f9163431" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_98cecd30-dd82-4c2b-bef5-90cb7ca5668a" xlink:to="loc_us-gaap_DebtSecuritiesMember_40e4020d-d8f4-4efa-8cfb-9635f9163431" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FixedIncomeFundsMember_fbc8da79-c070-4bd6-9835-d7934334eb3b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FixedIncomeFundsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtSecuritiesMember_40e4020d-d8f4-4efa-8cfb-9635f9163431" xlink:to="loc_us-gaap_FixedIncomeFundsMember_fbc8da79-c070-4bd6-9835-d7934334eb3b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_InsuranceContractMember_43700915-4db2-404b-b8e7-11896abfe603" xlink:href="hsc-20211231.xsd#hsc_InsuranceContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtSecuritiesMember_40e4020d-d8f4-4efa-8cfb-9635f9163431" xlink:to="loc_hsc_InsuranceContractMember_43700915-4db2-404b-b8e7-11896abfe603" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_OtherAssetCategoryMember_4e23dfcf-6d78-4687-94ad-298612a410c4" xlink:href="hsc-20211231.xsd#hsc_OtherAssetCategoryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_98cecd30-dd82-4c2b-bef5-90cb7ca5668a" xlink:to="loc_hsc_OtherAssetCategoryMember_4e23dfcf-6d78-4687-94ad-298612a410c4" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_OtherAssetCategoriesMutualFundsMember_d59e4380-80d9-4da7-99d9-5aadb2b3d802" xlink:href="hsc-20211231.xsd#hsc_OtherAssetCategoriesMutualFundsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hsc_OtherAssetCategoryMember_4e23dfcf-6d78-4687-94ad-298612a410c4" xlink:to="loc_hsc_OtherAssetCategoriesMutualFundsMember_d59e4380-80d9-4da7-99d9-5aadb2b3d802" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsMember_6b6f7876-cc4d-4447-97aa-9597d29ae5ef" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_98cecd30-dd82-4c2b-bef5-90cb7ca5668a" xlink:to="loc_us-gaap_CashAndCashEquivalentsMember_6b6f7876-cc4d-4447-97aa-9597d29ae5ef" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PartnershipMember_12fc63c7-2164-423f-af4e-8686ce53f9e6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PartnershipMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_98cecd30-dd82-4c2b-bef5-90cb7ca5668a" xlink:to="loc_us-gaap_PartnershipMember_12fc63c7-2164-423f-af4e-8686ce53f9e6" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanEquitySecuritiesCommonStockEmployerRelatedPartyMember_c256db6b-1cdf-4ae5-b8ae-a5ff07da9f96" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanEquitySecuritiesCommonStockEmployerRelatedPartyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_98cecd30-dd82-4c2b-bef5-90cb7ca5668a" xlink:to="loc_us-gaap_DefinedBenefitPlanEquitySecuritiesCommonStockEmployerRelatedPartyMember_c256db6b-1cdf-4ae5-b8ae-a5ff07da9f96" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_f1cdc472-5701-48f0-99a2-507aca090998" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_475c64d9-0bbe-4c75-873e-1982efb87c19" xlink:to="loc_srt_RangeAxis_f1cdc472-5701-48f0-99a2-507aca090998" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_f1cdc472-5701-48f0-99a2-507aca090998_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_f1cdc472-5701-48f0-99a2-507aca090998" xlink:to="loc_srt_RangeMember_f1cdc472-5701-48f0-99a2-507aca090998_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_7550caed-da8d-433a-8736-6f88a32b5681" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_f1cdc472-5701-48f0-99a2-507aca090998" xlink:to="loc_srt_RangeMember_7550caed-da8d-433a-8736-6f88a32b5681" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_d4d3a26b-67aa-46db-b50c-dc85d3c57258" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_7550caed-da8d-433a-8736-6f88a32b5681" xlink:to="loc_srt_MinimumMember_d4d3a26b-67aa-46db-b50c-dc85d3c57258" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_02597343-fba6-4439-aa86-616c2fe9307c" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_7550caed-da8d-433a-8736-6f88a32b5681" xlink:to="loc_srt_MaximumMember_02597343-fba6-4439-aa86-616c2fe9307c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_450ebb44-26b4-49a4-9924-4b6203e441f2" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_475c64d9-0bbe-4c75-873e-1982efb87c19" xlink:to="loc_srt_StatementScenarioAxis_450ebb44-26b4-49a4-9924-4b6203e441f2" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_450ebb44-26b4-49a4-9924-4b6203e441f2_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_450ebb44-26b4-49a4-9924-4b6203e441f2" xlink:to="loc_srt_ScenarioUnspecifiedDomain_450ebb44-26b4-49a4-9924-4b6203e441f2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_61221c00-bce1-48d3-babc-e16a980dc487" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_450ebb44-26b4-49a4-9924-4b6203e441f2" xlink:to="loc_srt_ScenarioUnspecifiedDomain_61221c00-bce1-48d3-babc-e16a980dc487" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioForecastMember_e4e83d1a-9a0b-42ca-ae66-62ae3d6afe17" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ScenarioForecastMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ScenarioUnspecifiedDomain_61221c00-bce1-48d3-babc-e16a980dc487" xlink:to="loc_srt_ScenarioForecastMember_e4e83d1a-9a0b-42ca-ae66-62ae3d6afe17" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/IncomeTaxesDetails2" xlink:type="simple" xlink:href="hsc-20211231.xsd#IncomeTaxesDetails2"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/IncomeTaxesDetails2" xlink:type="extended" id="ie00f60c707524e4cb61d5129b71d938d_IncomeTaxesDetails2">
    <link:loc xlink:type="locator" xlink:label="loc_hsc_IncomeTaxDisclosureLineItems_a6644d04-da2f-4366-ab32-7e2f78f5d294" xlink:href="hsc-20211231.xsd#hsc_IncomeTaxDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign_2b0e4708-904f-4aab-af79-688900272976" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hsc_IncomeTaxDisclosureLineItems_a6644d04-da2f-4366-ab32-7e2f78f5d294" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign_2b0e4708-904f-4aab-af79-688900272976" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_Differencesoninternationalearningsandremittances_eab42450-8fc3-4195-9c40-c3eb3849c19d" xlink:href="hsc-20211231.xsd#hsc_Differencesoninternationalearningsandremittances"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hsc_IncomeTaxDisclosureLineItems_a6644d04-da2f-4366-ab32-7e2f78f5d294" xlink:to="loc_hsc_Differencesoninternationalearningsandremittances_eab42450-8fc3-4195-9c40-c3eb3849c19d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_00efe5dd-9e26-4e1d-9a60-c18760780af8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hsc_IncomeTaxDisclosureLineItems_a6644d04-da2f-4366-ab32-7e2f78f5d294" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_00efe5dd-9e26-4e1d-9a60-c18760780af8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignIncomeTaxExpenseBenefitContinuingOperations_55dc26d1-6c65-478a-8157-c156a2d39574" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ForeignIncomeTaxExpenseBenefitContinuingOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hsc_IncomeTaxDisclosureLineItems_a6644d04-da2f-4366-ab32-7e2f78f5d294" xlink:to="loc_us-gaap_ForeignIncomeTaxExpenseBenefitContinuingOperations_55dc26d1-6c65-478a-8157-c156a2d39574" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_ab532bbf-0fb7-4025-8f80-be8284836163" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwards"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hsc_IncomeTaxDisclosureLineItems_a6644d04-da2f-4366-ab32-7e2f78f5d294" xlink:to="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_ab532bbf-0fb7-4025-8f80-be8284836163" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpiration_65351475-525d-4f6a-b499-b85b064350c0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpiration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hsc_IncomeTaxDisclosureLineItems_a6644d04-da2f-4366-ab32-7e2f78f5d294" xlink:to="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpiration_65351475-525d-4f6a-b499-b85b064350c0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration_6c9836e5-ffe6-4959-9764-cbef6ee08e77" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hsc_IncomeTaxDisclosureLineItems_a6644d04-da2f-4366-ab32-7e2f78f5d294" xlink:to="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration_6c9836e5-ffe6-4959-9764-cbef6ee08e77" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsValuationAllowance_3259d5f1-3774-411d-9b25-722be097697e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsValuationAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hsc_IncomeTaxDisclosureLineItems_a6644d04-da2f-4366-ab32-7e2f78f5d294" xlink:to="loc_us-gaap_DeferredTaxAssetsValuationAllowance_3259d5f1-3774-411d-9b25-722be097697e" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense_92320ebf-b0f4-4e70-9cc5-998cbe1642e7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hsc_IncomeTaxDisclosureLineItems_a6644d04-da2f-4366-ab32-7e2f78f5d294" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense_92320ebf-b0f4-4e70-9cc5-998cbe1642e7" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued_d446e7e7-5adf-4904-b62d-97a5045de945" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hsc_IncomeTaxDisclosureLineItems_a6644d04-da2f-4366-ab32-7e2f78f5d294" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued_d446e7e7-5adf-4904-b62d-97a5045de945" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleAmountOfUnrecordedBenefit_ec7754de-5bc4-440a-bd60-784ba798ec6f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleAmountOfUnrecordedBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hsc_IncomeTaxDisclosureLineItems_a6644d04-da2f-4366-ab32-7e2f78f5d294" xlink:to="loc_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleAmountOfUnrecordedBenefit_ec7754de-5bc4-440a-bd60-784ba798ec6f" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CurrentForeignTaxExpenseBenefit_9ecc42b4-4df0-44a2-96a4-3db2993daaee" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CurrentForeignTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hsc_IncomeTaxDisclosureLineItems_a6644d04-da2f-4366-ab32-7e2f78f5d294" xlink:to="loc_us-gaap_CurrentForeignTaxExpenseBenefit_9ecc42b4-4df0-44a2-96a4-3db2993daaee" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_IncomeTaxDisclosureTable_8aceab25-aa53-4e84-bbea-d28a6053df8b" xlink:href="hsc-20211231.xsd#hsc_IncomeTaxDisclosureTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_hsc_IncomeTaxDisclosureLineItems_a6644d04-da2f-4366-ab32-7e2f78f5d294" xlink:to="loc_hsc_IncomeTaxDisclosureTable_8aceab25-aa53-4e84-bbea-d28a6053df8b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_d7d78b33-06d7-4007-ab37-e1ebfc6701f0" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_hsc_IncomeTaxDisclosureTable_8aceab25-aa53-4e84-bbea-d28a6053df8b" xlink:to="loc_srt_StatementGeographicalAxis_d7d78b33-06d7-4007-ab37-e1ebfc6701f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_d7d78b33-06d7-4007-ab37-e1ebfc6701f0_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_d7d78b33-06d7-4007-ab37-e1ebfc6701f0" xlink:to="loc_srt_SegmentGeographicalDomain_d7d78b33-06d7-4007-ab37-e1ebfc6701f0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_17ca0493-79e6-42c6-8649-6b9c3b78417f" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_d7d78b33-06d7-4007-ab37-e1ebfc6701f0" xlink:to="loc_srt_SegmentGeographicalDomain_17ca0493-79e6-42c6-8649-6b9c3b78417f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_bbf0ac6f-0364-41cc-bf8c-d87e25621e40" xlink:href="https://xbrl.sec.gov/country/2021/country-2021.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_17ca0493-79e6-42c6-8649-6b9c3b78417f" xlink:to="loc_country_US_bbf0ac6f-0364-41cc-bf8c-d87e25621e40" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_BR_2b32aa77-2392-401f-9fd1-d4189ea1d013" xlink:href="https://xbrl.sec.gov/country/2021/country-2021.xsd#country_BR"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_17ca0493-79e6-42c6-8649-6b9c3b78417f" xlink:to="loc_country_BR_2b32aa77-2392-401f-9fd1-d4189ea1d013" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_d2790cdc-07d6-4230-b010-c7098ff5d3c9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeTaxAuthorityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_hsc_IncomeTaxDisclosureTable_8aceab25-aa53-4e84-bbea-d28a6053df8b" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_d2790cdc-07d6-4230-b010-c7098ff5d3c9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_d2790cdc-07d6-4230-b010-c7098ff5d3c9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_d2790cdc-07d6-4230-b010-c7098ff5d3c9" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_d2790cdc-07d6-4230-b010-c7098ff5d3c9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_1c4a77a7-3dac-4f2b-b852-edc8f209efd9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_d2790cdc-07d6-4230-b010-c7098ff5d3c9" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_1c4a77a7-3dac-4f2b-b852-edc8f209efd9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCountryMember_f21f94cd-7dbf-4b0b-b7ac-502f30f2b2c1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ForeignCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_1c4a77a7-3dac-4f2b-b852-edc8f209efd9" xlink:to="loc_us-gaap_ForeignCountryMember_f21f94cd-7dbf-4b0b-b7ac-502f30f2b2c1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember_7d66e05d-4db8-422c-90f9-126216445036" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StateAndLocalJurisdictionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_1c4a77a7-3dac-4f2b-b852-edc8f209efd9" xlink:to="loc_us-gaap_StateAndLocalJurisdictionMember_7d66e05d-4db8-422c-90f9-126216445036" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_1c1260a6-62a8-470e-8806-cae5c2b05b33" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_hsc_IncomeTaxDisclosureTable_8aceab25-aa53-4e84-bbea-d28a6053df8b" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_1c1260a6-62a8-470e-8806-cae5c2b05b33" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_1c1260a6-62a8-470e-8806-cae5c2b05b33_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_1c1260a6-62a8-470e-8806-cae5c2b05b33" xlink:to="loc_us-gaap_SegmentDomain_1c1260a6-62a8-470e-8806-cae5c2b05b33_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_f8f33504-f719-41de-a062-d7ec53fae76c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_1c1260a6-62a8-470e-8806-cae5c2b05b33" xlink:to="loc_us-gaap_SegmentDomain_f8f33504-f719-41de-a062-d7ec53fae76c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoEnvironmentalSegmentMember_4ae628ba-1de5-4403-b538-522bf5084b9d" xlink:href="hsc-20211231.xsd#hsc_HarscoEnvironmentalSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_f8f33504-f719-41de-a062-d7ec53fae76c" xlink:to="loc_hsc_HarscoEnvironmentalSegmentMember_4ae628ba-1de5-4403-b538-522bf5084b9d" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/IncomeTaxesDetails4" xlink:type="simple" xlink:href="hsc-20211231.xsd#IncomeTaxesDetails4"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/IncomeTaxesDetails4" xlink:type="extended" id="if56d9df2a24a4ed0803a671da1d643df_IncomeTaxesDetails4">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwardsLineItems_64042af3-eabf-438e-8483-6817bd95b82d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLossCarryforwardsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic_4c28bfb4-38e7-489f-a372-a29d10d93140" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_64042af3-eabf-438e-8483-6817bd95b82d" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic_4c28bfb4-38e7-489f-a372-a29d10d93140" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration_645ca52a-9a70-47af-b9e0-b66175b3282a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_64042af3-eabf-438e-8483-6817bd95b82d" xlink:to="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration_645ca52a-9a70-47af-b9e0-b66175b3282a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpiration_72004644-9825-4a46-99aa-aaae53f6f746" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpiration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_64042af3-eabf-438e-8483-6817bd95b82d" xlink:to="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpiration_72004644-9825-4a46-99aa-aaae53f6f746" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense_cb0730bc-e4e6-48dc-9908-75055e4eec59" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_64042af3-eabf-438e-8483-6817bd95b82d" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense_cb0730bc-e4e6-48dc-9908-75055e4eec59" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComponentsOfDeferredTaxAssetsAndLiabilitiesAbstract_d4a0b265-5aae-4df3-af60-496068053a12" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ComponentsOfDeferredTaxAssetsAndLiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_64042af3-eabf-438e-8483-6817bd95b82d" xlink:to="loc_us-gaap_ComponentsOfDeferredTaxAssetsAndLiabilitiesAbstract_d4a0b265-5aae-4df3-af60-496068053a12" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComponentsOfDeferredTaxAssetsAbstract_bab7f19a-3cab-49b2-b3ef-6ccbfcecc28d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ComponentsOfDeferredTaxAssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxAssetsAndLiabilitiesAbstract_d4a0b265-5aae-4df3-af60-496068053a12" xlink:to="loc_us-gaap_ComponentsOfDeferredTaxAssetsAbstract_bab7f19a-3cab-49b2-b3ef-6ccbfcecc28d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsPropertyPlantAndEquipment_af24e5f3-f78d-4bdf-b5e1-3f25e7cdf5e2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxAssetsAbstract_bab7f19a-3cab-49b2-b3ef-6ccbfcecc28d" xlink:to="loc_us-gaap_DeferredTaxAssetsPropertyPlantAndEquipment_af24e5f3-f78d-4bdf-b5e1-3f25e7cdf5e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DeferredTaxAssetOperatingLeaseLiabilities_a19e57b3-663a-40ce-b6cf-a216e7c093ca" xlink:href="hsc-20211231.xsd#hsc_DeferredTaxAssetOperatingLeaseLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxAssetsAbstract_bab7f19a-3cab-49b2-b3ef-6ccbfcecc28d" xlink:to="loc_hsc_DeferredTaxAssetOperatingLeaseLiabilities_a19e57b3-663a-40ce-b6cf-a216e7c093ca" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities_71ed79a4-d519-44d2-be3c-6bf24de69429" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxAssetsAbstract_bab7f19a-3cab-49b2-b3ef-6ccbfcecc28d" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities_71ed79a4-d519-44d2-be3c-6bf24de69429" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsInventory_4b569c55-808e-45bb-8470-6de86d6483f9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsInventory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxAssetsAbstract_bab7f19a-3cab-49b2-b3ef-6ccbfcecc28d" xlink:to="loc_us-gaap_DeferredTaxAssetsInventory_4b569c55-808e-45bb-8470-6de86d6483f9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts_d36cb2e1-8e97-4b14-9c6c-b001618cb98e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxAssetsAbstract_bab7f19a-3cab-49b2-b3ef-6ccbfcecc28d" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAllowanceForDoubtfulAccounts_d36cb2e1-8e97-4b14-9c6c-b001618cb98e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_11eaed3e-180d-453c-b184-5f074c7b41c4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwards"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxAssetsAbstract_bab7f19a-3cab-49b2-b3ef-6ccbfcecc28d" xlink:to="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_11eaed3e-180d-453c-b184-5f074c7b41c4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsForeign_056c7f33-ba95-4791-b8fe-ca5e2d15a860" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsForeign"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxAssetsAbstract_bab7f19a-3cab-49b2-b3ef-6ccbfcecc28d" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsForeign_056c7f33-ba95-4791-b8fe-ca5e2d15a860" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPensions_61735a19-04c4-4888-b6bf-de36b3051da2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPensions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxAssetsAbstract_bab7f19a-3cab-49b2-b3ef-6ccbfcecc28d" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPensions_61735a19-04c4-4888-b6bf-de36b3051da2" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsUnrealizedCurrencyLosses_e50d06f0-37d7-4b4a-85e6-dc3a547ef999" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsUnrealizedCurrencyLosses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxAssetsAbstract_bab7f19a-3cab-49b2-b3ef-6ccbfcecc28d" xlink:to="loc_us-gaap_DeferredTaxAssetsUnrealizedCurrencyLosses_e50d06f0-37d7-4b4a-85e6-dc3a547ef999" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DeferredTaxAssetDeferredFinancingCost_df49efa8-bdf0-4f96-b62c-8c30113f56f3" xlink:href="hsc-20211231.xsd#hsc_DeferredTaxAssetDeferredFinancingCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxAssetsAbstract_bab7f19a-3cab-49b2-b3ef-6ccbfcecc28d" xlink:to="loc_hsc_DeferredTaxAssetDeferredFinancingCost_df49efa8-bdf0-4f96-b62c-8c30113f56f3" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DeferredTaxAssetDisallowedInterestExpense_e795ee1c-e1b2-4863-af43-a973c23f3a34" xlink:href="hsc-20211231.xsd#hsc_DeferredTaxAssetDisallowedInterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxAssetsAbstract_bab7f19a-3cab-49b2-b3ef-6ccbfcecc28d" xlink:to="loc_hsc_DeferredTaxAssetDisallowedInterestExpense_e795ee1c-e1b2-4863-af43-a973c23f3a34" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPostretirementBenefits_b2eb4f5f-8061-4629-8c1f-f776af4971d4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPostretirementBenefits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxAssetsAbstract_bab7f19a-3cab-49b2-b3ef-6ccbfcecc28d" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPostretirementBenefits_b2eb4f5f-8061-4629-8c1f-f776af4971d4" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost_41eb47a9-cdd5-4e0a-ad0b-9e857dc5c2c3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxAssetsAbstract_bab7f19a-3cab-49b2-b3ef-6ccbfcecc28d" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost_41eb47a9-cdd5-4e0a-ad0b-9e857dc5c2c3" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsOther_b160cf6d-a43b-4f71-86f1-d4d746c50eec" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxAssetsAbstract_bab7f19a-3cab-49b2-b3ef-6ccbfcecc28d" xlink:to="loc_us-gaap_DeferredTaxAssetsOther_b160cf6d-a43b-4f71-86f1-d4d746c50eec" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsGross_32666a45-3c93-4446-868b-4e855b19c540" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxAssetsAbstract_bab7f19a-3cab-49b2-b3ef-6ccbfcecc28d" xlink:to="loc_us-gaap_DeferredTaxAssetsGross_32666a45-3c93-4446-868b-4e855b19c540" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsValuationAllowance_c7a0eefe-031b-4a0f-b130-e8b3c744d3ba" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsValuationAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxAssetsAbstract_bab7f19a-3cab-49b2-b3ef-6ccbfcecc28d" xlink:to="loc_us-gaap_DeferredTaxAssetsValuationAllowance_c7a0eefe-031b-4a0f-b130-e8b3c744d3ba" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsNet_1cd98faf-c11a-434e-b345-21946531e39d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxAssetsAbstract_bab7f19a-3cab-49b2-b3ef-6ccbfcecc28d" xlink:to="loc_us-gaap_DeferredTaxAssetsNet_1cd98faf-c11a-434e-b345-21946531e39d" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract_ef13689f-052c-43f7-a5e2-59a222e4a45a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxAssetsAndLiabilitiesAbstract_d4a0b265-5aae-4df3-af60-496068053a12" xlink:to="loc_us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract_ef13689f-052c-43f7-a5e2-59a222e4a45a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment_0b0e3439-ab71-4960-bf22-56f13d69fb8c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract_ef13689f-052c-43f7-a5e2-59a222e4a45a" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment_0b0e3439-ab71-4960-bf22-56f13d69fb8c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DeferredTaxLiabilityRightOfUseAssets_5baab3f6-809f-4a2b-a441-9b277ed8aaf5" xlink:href="hsc-20211231.xsd#hsc_DeferredTaxLiabilityRightOfUseAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract_ef13689f-052c-43f7-a5e2-59a222e4a45a" xlink:to="loc_hsc_DeferredTaxLiabilityRightOfUseAssets_5baab3f6-809f-4a2b-a441-9b277ed8aaf5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesTaxDeferredIncome_448adc58-2d3b-440a-aa32-4f61e7468a54" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxLiabilitiesTaxDeferredIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract_ef13689f-052c-43f7-a5e2-59a222e4a45a" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesTaxDeferredIncome_448adc58-2d3b-440a-aa32-4f61e7468a54" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesFinancingArrangements_e89006d9-2563-4df2-ba82-eecb51f405d5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxLiabilitiesFinancingArrangements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract_ef13689f-052c-43f7-a5e2-59a222e4a45a" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesFinancingArrangements_e89006d9-2563-4df2-ba82-eecb51f405d5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesOther_283c8a86-b6b2-4c2d-9e83-138f4489935f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxLiabilitiesOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract_ef13689f-052c-43f7-a5e2-59a222e4a45a" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesOther_283c8a86-b6b2-4c2d-9e83-138f4489935f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilities_c61ab25a-0d79-42b0-ad70-5cca9bcf7893" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredIncomeTaxLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract_ef13689f-052c-43f7-a5e2-59a222e4a45a" xlink:to="loc_us-gaap_DeferredIncomeTaxLiabilities_c61ab25a-0d79-42b0-ad70-5cca9bcf7893" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsLiabilitiesNetAbstract_1e894fea-1313-4048-89f0-98cc746b17b9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetsLiabilitiesNetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxAssetsAndLiabilitiesAbstract_d4a0b265-5aae-4df3-af60-496068053a12" xlink:to="loc_us-gaap_DeferredTaxAssetsLiabilitiesNetAbstract_1e894fea-1313-4048-89f0-98cc746b17b9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxAssetsNet_0eea6d12-3917-433a-beb5-8e8082e31970" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredIncomeTaxAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxAssetsLiabilitiesNetAbstract_1e894fea-1313-4048-89f0-98cc746b17b9" xlink:to="loc_us-gaap_DeferredIncomeTaxAssetsNet_0eea6d12-3917-433a-beb5-8e8082e31970" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_000d2725-4b80-4772-8682-840f7f9fcb74" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredIncomeTaxLiabilitiesNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxAssetsLiabilitiesNetAbstract_1e894fea-1313-4048-89f0-98cc746b17b9" xlink:to="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_000d2725-4b80-4772-8682-840f7f9fcb74" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ValuationAllowanceDeferredTaxAssetDecreaseFromPensionAdjustment_7872d8bf-9231-4f4b-914f-4ace39528b4b" xlink:href="hsc-20211231.xsd#hsc_ValuationAllowanceDeferredTaxAssetDecreaseFromPensionAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_64042af3-eabf-438e-8483-6817bd95b82d" xlink:to="loc_hsc_ValuationAllowanceDeferredTaxAssetDecreaseFromPensionAdjustment_7872d8bf-9231-4f4b-914f-4ace39528b4b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ValuationAllowanceDeferredTaxAssetDecreaseFromAssetValuation_46b4f485-ce50-45de-9246-1e3193b29648" xlink:href="hsc-20211231.xsd#hsc_ValuationAllowanceDeferredTaxAssetDecreaseFromAssetValuation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_64042af3-eabf-438e-8483-6817bd95b82d" xlink:to="loc_hsc_ValuationAllowanceDeferredTaxAssetDecreaseFromAssetValuation_46b4f485-ce50-45de-9246-1e3193b29648" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ValuationAllowanceDeferredTaxAssetIncreaseFromTaxRateAdjustment_1cf626b1-59be-4d74-ac45-8f46c0d33122" xlink:href="hsc-20211231.xsd#hsc_ValuationAllowanceDeferredTaxAssetIncreaseFromTaxRateAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_64042af3-eabf-438e-8483-6817bd95b82d" xlink:to="loc_hsc_ValuationAllowanceDeferredTaxAssetIncreaseFromTaxRateAdjustment_1cf626b1-59be-4d74-ac45-8f46c0d33122" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ValuationAllowanceDeferredTaxAssetReductionRelatedToDisallowedInterestExpense_5e23645d-c315-4743-a6e3-ed406eddd072" xlink:href="hsc-20211231.xsd#hsc_ValuationAllowanceDeferredTaxAssetReductionRelatedToDisallowedInterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_64042af3-eabf-438e-8483-6817bd95b82d" xlink:to="loc_hsc_ValuationAllowanceDeferredTaxAssetReductionRelatedToDisallowedInterestExpense_5e23645d-c315-4743-a6e3-ed406eddd072" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ValuationAllowanceDeferredTaxAssetDecreaseFromForeignCurrencyTranslationAdjustment_1d5bdac6-f5db-4bb2-a005-0b05801a6322" xlink:href="hsc-20211231.xsd#hsc_ValuationAllowanceDeferredTaxAssetDecreaseFromForeignCurrencyTranslationAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_64042af3-eabf-438e-8483-6817bd95b82d" xlink:to="loc_hsc_ValuationAllowanceDeferredTaxAssetDecreaseFromForeignCurrencyTranslationAdjustment_1d5bdac6-f5db-4bb2-a005-0b05801a6322" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_6384fbd3-222b-4301-8f67-cdbdf97962f8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_64042af3-eabf-438e-8483-6817bd95b82d" xlink:to="loc_us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_6384fbd3-222b-4301-8f67-cdbdf97962f8" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwardsTable_782b84e9-7e55-4fbc-aaaa-79a782ba745a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLossCarryforwardsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_64042af3-eabf-438e-8483-6817bd95b82d" xlink:to="loc_us-gaap_OperatingLossCarryforwardsTable_782b84e9-7e55-4fbc-aaaa-79a782ba745a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_a38839fb-eb8c-4e09-9769-beadccb65807" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeTaxAuthorityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_782b84e9-7e55-4fbc-aaaa-79a782ba745a" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_a38839fb-eb8c-4e09-9769-beadccb65807" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_a38839fb-eb8c-4e09-9769-beadccb65807_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_a38839fb-eb8c-4e09-9769-beadccb65807" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_a38839fb-eb8c-4e09-9769-beadccb65807_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_46b51240-9199-49ea-99bf-e55e2be267dd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_a38839fb-eb8c-4e09-9769-beadccb65807" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_46b51240-9199-49ea-99bf-e55e2be267dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DomesticCountryMember_fd03aacb-be4e-4011-8813-ef71d8022911" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DomesticCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_46b51240-9199-49ea-99bf-e55e2be267dd" xlink:to="loc_us-gaap_DomesticCountryMember_fd03aacb-be4e-4011-8813-ef71d8022911" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember_a9d08f15-170e-4317-a0be-7c3fa1656951" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StateAndLocalJurisdictionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DomesticCountryMember_fd03aacb-be4e-4011-8813-ef71d8022911" xlink:to="loc_us-gaap_StateAndLocalJurisdictionMember_a9d08f15-170e-4317-a0be-7c3fa1656951" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCountryMember_33c8d4f6-ae2b-40e7-a973-7958696d46c0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ForeignCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_46b51240-9199-49ea-99bf-e55e2be267dd" xlink:to="loc_us-gaap_ForeignCountryMember_33c8d4f6-ae2b-40e7-a973-7958696d46c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember_7ef98c45-3ff4-4954-9cb5-2b2553eb6b5a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StateAndLocalJurisdictionMember"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxPeriodAxis_ee8145ed-3ee3-41db-b36e-c54612db2dec" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TaxPeriodAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_782b84e9-7e55-4fbc-aaaa-79a782ba745a" xlink:to="loc_us-gaap_TaxPeriodAxis_ee8145ed-3ee3-41db-b36e-c54612db2dec" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxPeriodDomain_ee8145ed-3ee3-41db-b36e-c54612db2dec_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TaxPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TaxPeriodAxis_ee8145ed-3ee3-41db-b36e-c54612db2dec" xlink:to="loc_us-gaap_TaxPeriodDomain_ee8145ed-3ee3-41db-b36e-c54612db2dec_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxPeriodDomain_a36636a0-4d46-4242-9dbe-325c358968ac" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TaxPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TaxPeriodAxis_ee8145ed-3ee3-41db-b36e-c54612db2dec" xlink:to="loc_us-gaap_TaxPeriodDomain_a36636a0-4d46-4242-9dbe-325c358968ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_TaxYears2021Through2025Member_098cd639-6a16-42e8-80b4-d97f230c6fc1" xlink:href="hsc-20211231.xsd#hsc_TaxYears2021Through2025Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxPeriodDomain_a36636a0-4d46-4242-9dbe-325c358968ac" xlink:to="loc_hsc_TaxYears2021Through2025Member_098cd639-6a16-42e8-80b4-d97f230c6fc1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_TaxYears2026Through2030Member_80f8efe8-a4d8-484e-9b62-5c03d2878d12" xlink:href="hsc-20211231.xsd#hsc_TaxYears2026Through2030Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxPeriodDomain_a36636a0-4d46-4242-9dbe-325c358968ac" xlink:to="loc_hsc_TaxYears2026Through2030Member_80f8efe8-a4d8-484e-9b62-5c03d2878d12" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_TaxYears2031Through2035Member_4672f87a-3c46-4ddb-8623-7222aa6cdcc6" xlink:href="hsc-20211231.xsd#hsc_TaxYears2031Through2035Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxPeriodDomain_a36636a0-4d46-4242-9dbe-325c358968ac" xlink:to="loc_hsc_TaxYears2031Through2035Member_4672f87a-3c46-4ddb-8623-7222aa6cdcc6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_TaxYears2036Through2040Member_0f33071b-5e08-4559-9091-2e98f11c245c" xlink:href="hsc-20211231.xsd#hsc_TaxYears2036Through2040Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxPeriodDomain_a36636a0-4d46-4242-9dbe-325c358968ac" xlink:to="loc_hsc_TaxYears2036Through2040Member_0f33071b-5e08-4559-9091-2e98f11c245c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_TaxYears2021Through2040Member_c1bfbb4c-489c-42d7-9a36-3baa1c0dd8b7" xlink:href="hsc-20211231.xsd#hsc_TaxYears2021Through2040Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxPeriodDomain_a36636a0-4d46-4242-9dbe-325c358968ac" xlink:to="loc_hsc_TaxYears2021Through2040Member_c1bfbb4c-489c-42d7-9a36-3baa1c0dd8b7" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/CommitmentsandContingenciesDetails" xlink:type="simple" xlink:href="hsc-20211231.xsd#CommitmentsandContingenciesDetails"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/CommitmentsandContingenciesDetails" xlink:type="extended" id="i44ac5de2f5ba484e81fe269bca33f370_CommitmentsandContingenciesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_adb810da-ec0f-4087-9b7d-fea0b8d89565" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_LossContingencyDamagesSoughtPrincipalAmount_35b97355-343d-444a-8bc8-bac39334b007" xlink:href="hsc-20211231.xsd#hsc_LossContingencyDamagesSoughtPrincipalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_adb810da-ec0f-4087-9b7d-fea0b8d89565" xlink:to="loc_hsc_LossContingencyDamagesSoughtPrincipalAmount_35b97355-343d-444a-8bc8-bac39334b007" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_LossContingencyDamagesSoughtInterestPenaltiesAndFees_d1d39600-e7d4-4e17-b062-c2381a3d5b41" xlink:href="hsc-20211231.xsd#hsc_LossContingencyDamagesSoughtInterestPenaltiesAndFees"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_adb810da-ec0f-4087-9b7d-fea0b8d89565" xlink:to="loc_hsc_LossContingencyDamagesSoughtInterestPenaltiesAndFees_d1d39600-e7d4-4e17-b062-c2381a3d5b41" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyPendingClaimsNumber_c41b5a8e-1d37-4977-aee3-524f948d14fc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LossContingencyPendingClaimsNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_adb810da-ec0f-4087-9b7d-fea0b8d89565" xlink:to="loc_us-gaap_LossContingencyPendingClaimsNumber_c41b5a8e-1d37-4977-aee3-524f948d14fc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyDamagesSoughtValue_160cceea-e0fb-4c41-b10f-3e07b9fb4da0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LossContingencyDamagesSoughtValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_adb810da-ec0f-4087-9b7d-fea0b8d89565" xlink:to="loc_us-gaap_LossContingencyDamagesSoughtValue_160cceea-e0fb-4c41-b10f-3e07b9fb4da0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualProvision_8349caf6-f6b8-497b-8cc7-5ec74a88045f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LossContingencyAccrualProvision"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_adb810da-ec0f-4087-9b7d-fea0b8d89565" xlink:to="loc_us-gaap_LossContingencyAccrualProvision_8349caf6-f6b8-497b-8cc7-5ec74a88045f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualAtCarryingValue_8ef459fb-aa9f-4f5c-b1ff-9865ad3810da" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LossContingencyAccrualAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_adb810da-ec0f-4087-9b7d-fea0b8d89565" xlink:to="loc_us-gaap_LossContingencyAccrualAtCarryingValue_8ef459fb-aa9f-4f5c-b1ff-9865ad3810da" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccrualForEnvironmentalLossContingencies_bb9994fb-60c2-48fa-8715-5cfdd7335180" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccrualForEnvironmentalLossContingencies"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_adb810da-ec0f-4087-9b7d-fea0b8d89565" xlink:to="loc_us-gaap_AccrualForEnvironmentalLossContingencies_bb9994fb-60c2-48fa-8715-5cfdd7335180" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_Penaltiesperday_7760c95c-d3b0-464f-b4bd-0ef1efc485c8" xlink:href="hsc-20211231.xsd#hsc_Penaltiesperday"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_adb810da-ec0f-4087-9b7d-fea0b8d89565" xlink:to="loc_hsc_Penaltiesperday_7760c95c-d3b0-464f-b4bd-0ef1efc485c8" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_Penalties_84514b4e-86cf-420c-82b5-626f99eb3d05" xlink:href="hsc-20211231.xsd#hsc_Penalties"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_adb810da-ec0f-4087-9b7d-fea0b8d89565" xlink:to="loc_hsc_Penalties_84514b4e-86cf-420c-82b5-626f99eb3d05" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNumberOfDefendants_31b3b875-b08c-4ee5-8c1d-7d3fddc862c9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LossContingencyNumberOfDefendants"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_adb810da-ec0f-4087-9b7d-fea0b8d89565" xlink:to="loc_us-gaap_LossContingencyNumberOfDefendants_31b3b875-b08c-4ee5-8c1d-7d3fddc862c9" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyClaimsDismissedNumber_3ddea859-eeda-4ee0-bbc6-3a01f5b02585" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LossContingencyClaimsDismissedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_adb810da-ec0f-4087-9b7d-fea0b8d89565" xlink:to="loc_us-gaap_LossContingencyClaimsDismissedNumber_3ddea859-eeda-4ee0-bbc6-3a01f5b02585" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_LossContingenciesUnpaidServiceTaxes_5a5eb0aa-4d55-41c8-ac12-ffce6ffbac81" xlink:href="hsc-20211231.xsd#hsc_LossContingenciesUnpaidServiceTaxes"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_adb810da-ec0f-4087-9b7d-fea0b8d89565" xlink:to="loc_hsc_LossContingenciesUnpaidServiceTaxes_5a5eb0aa-4d55-41c8-ac12-ffce6ffbac81" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_LossContingenciesOverallLiability_c621ff5d-c1c5-4011-8a0d-08b59b6a228f" xlink:href="hsc-20211231.xsd#hsc_LossContingenciesOverallLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_adb810da-ec0f-4087-9b7d-fea0b8d89565" xlink:to="loc_hsc_LossContingenciesOverallLiability_c621ff5d-c1c5-4011-8a0d-08b59b6a228f" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ProposedCivilPenalty_5cde2e72-cfbe-4ad1-b82b-35bf8df86330" xlink:href="hsc-20211231.xsd#hsc_ProposedCivilPenalty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_adb810da-ec0f-4087-9b7d-fea0b8d89565" xlink:to="loc_hsc_ProposedCivilPenalty_5cde2e72-cfbe-4ad1-b82b-35bf8df86330" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_fac4003a-409a-48ab-9bcc-6df60099a4fe" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_adb810da-ec0f-4087-9b7d-fea0b8d89565" xlink:to="loc_us-gaap_LossContingenciesTable_fac4003a-409a-48ab-9bcc-6df60099a4fe" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_d3e2d16c-fdb3-48f1-96b0-375eff467543" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_fac4003a-409a-48ab-9bcc-6df60099a4fe" xlink:to="loc_srt_MajorCustomersAxis_d3e2d16c-fdb3-48f1-96b0-375eff467543" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_d3e2d16c-fdb3-48f1-96b0-375eff467543_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_d3e2d16c-fdb3-48f1-96b0-375eff467543" xlink:to="loc_srt_NameOfMajorCustomerDomain_d3e2d16c-fdb3-48f1-96b0-375eff467543_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_f36ae570-928f-4851-a66a-1231fd8c0566" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_d3e2d16c-fdb3-48f1-96b0-375eff467543" xlink:to="loc_srt_NameOfMajorCustomerDomain_f36ae570-928f-4851-a66a-1231fd8c0566" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_CSNMember_296e7614-8923-4331-8894-8c7bf1b23013" xlink:href="hsc-20211231.xsd#hsc_CSNMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_f36ae570-928f-4851-a66a-1231fd8c0566" xlink:to="loc_hsc_CSNMember_296e7614-8923-4331-8894-8c7bf1b23013" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_233fe126-d0cc-42d5-a4ea-96f9154d5da0" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_LitigationCaseAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_fac4003a-409a-48ab-9bcc-6df60099a4fe" xlink:to="loc_srt_LitigationCaseAxis_233fe126-d0cc-42d5-a4ea-96f9154d5da0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_233fe126-d0cc-42d5-a4ea-96f9154d5da0_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_233fe126-d0cc-42d5-a4ea-96f9154d5da0" xlink:to="loc_srt_LitigationCaseTypeDomain_233fe126-d0cc-42d5-a4ea-96f9154d5da0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_fbbfe4e7-8acf-4ecb-bfd1-d7c3e4e148f4" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_233fe126-d0cc-42d5-a4ea-96f9154d5da0" xlink:to="loc_srt_LitigationCaseTypeDomain_fbbfe4e7-8acf-4ecb-bfd1-d7c3e4e148f4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatutoryAccountingPracticesByJurisdictionAxis_3e480373-2afc-48f8-b0aa-2c4cd13263d8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatutoryAccountingPracticesByJurisdictionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_fac4003a-409a-48ab-9bcc-6df60099a4fe" xlink:to="loc_us-gaap_StatutoryAccountingPracticesByJurisdictionAxis_3e480373-2afc-48f8-b0aa-2c4cd13263d8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatutoryAccountingPracticesJurisdictionDomain_3e480373-2afc-48f8-b0aa-2c4cd13263d8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatutoryAccountingPracticesJurisdictionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatutoryAccountingPracticesByJurisdictionAxis_3e480373-2afc-48f8-b0aa-2c4cd13263d8" xlink:to="loc_us-gaap_StatutoryAccountingPracticesJurisdictionDomain_3e480373-2afc-48f8-b0aa-2c4cd13263d8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatutoryAccountingPracticesJurisdictionDomain_763c18c1-8f01-4846-992a-46360c0d06f4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatutoryAccountingPracticesJurisdictionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatutoryAccountingPracticesByJurisdictionAxis_3e480373-2afc-48f8-b0aa-2c4cd13263d8" xlink:to="loc_us-gaap_StatutoryAccountingPracticesJurisdictionDomain_763c18c1-8f01-4846-992a-46360c0d06f4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_SaoPauloStateRevenueAuthorityMember_08bc2772-1ad8-4111-b5c5-467feab196f3" xlink:href="hsc-20211231.xsd#hsc_SaoPauloStateRevenueAuthorityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatutoryAccountingPracticesJurisdictionDomain_763c18c1-8f01-4846-992a-46360c0d06f4" xlink:to="loc_hsc_SaoPauloStateRevenueAuthorityMember_08bc2772-1ad8-4111-b5c5-467feab196f3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_NewYorkCountyAsManagedByNewYorkSupremeCourtMember_8e631ee6-61fa-4ba1-a71e-125af9add29a" xlink:href="hsc-20211231.xsd#hsc_NewYorkCountyAsManagedByNewYorkSupremeCourtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatutoryAccountingPracticesJurisdictionDomain_763c18c1-8f01-4846-992a-46360c0d06f4" xlink:to="loc_hsc_NewYorkCountyAsManagedByNewYorkSupremeCourtMember_8e631ee6-61fa-4ba1-a71e-125af9add29a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_NewYorkStateSupremeCourtCountiesExcludingNewYorkCountyMember_2332acfe-cf9e-40b8-981f-47f2b9a2460c" xlink:href="hsc-20211231.xsd#hsc_NewYorkStateSupremeCourtCountiesExcludingNewYorkCountyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatutoryAccountingPracticesJurisdictionDomain_763c18c1-8f01-4846-992a-46360c0d06f4" xlink:to="loc_hsc_NewYorkStateSupremeCourtCountiesExcludingNewYorkCountyMember_2332acfe-cf9e-40b8-981f-47f2b9a2460c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_CourtsLocatedInStatesOtherThanNewYorkMember_51bd6bf5-5cbe-445e-b1b1-66825f951e8e" xlink:href="hsc-20211231.xsd#hsc_CourtsLocatedInStatesOtherThanNewYorkMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatutoryAccountingPracticesJurisdictionDomain_763c18c1-8f01-4846-992a-46360c0d06f4" xlink:to="loc_hsc_CourtsLocatedInStatesOtherThanNewYorkMember_51bd6bf5-5cbe-445e-b1b1-66825f951e8e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_BR_6b3e87bb-44e8-4172-a4f0-28ebd03d13e1" xlink:href="https://xbrl.sec.gov/country/2021/country-2021.xsd#country_BR"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatutoryAccountingPracticesJurisdictionDomain_763c18c1-8f01-4846-992a-46360c0d06f4" xlink:to="loc_country_BR_6b3e87bb-44e8-4172-a4f0-28ebd03d13e1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusAxis_14e614d1-4d59-4bb1-9868-ca59e4e12ef5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LitigationStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_fac4003a-409a-48ab-9bcc-6df60099a4fe" xlink:to="loc_us-gaap_LitigationStatusAxis_14e614d1-4d59-4bb1-9868-ca59e4e12ef5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_14e614d1-4d59-4bb1-9868-ca59e4e12ef5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationStatusAxis_14e614d1-4d59-4bb1-9868-ca59e4e12ef5" xlink:to="loc_us-gaap_LitigationStatusDomain_14e614d1-4d59-4bb1-9868-ca59e4e12ef5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_b32233f2-a08f-4720-83ba-7f54db5216ca" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationStatusAxis_14e614d1-4d59-4bb1-9868-ca59e4e12ef5" xlink:to="loc_us-gaap_LitigationStatusDomain_b32233f2-a08f-4720-83ba-7f54db5216ca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_PendingAndFutureLitigationDeferredOrInactiveDocketMember_ab385e11-9eb7-4360-bf00-5a901b4a7f41" xlink:href="hsc-20211231.xsd#hsc_PendingAndFutureLitigationDeferredOrInactiveDocketMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_b32233f2-a08f-4720-83ba-7f54db5216ca" xlink:to="loc_hsc_PendingAndFutureLitigationDeferredOrInactiveDocketMember_ab385e11-9eb7-4360-bf00-5a901b4a7f41" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_PendingLitigationActiveOrInExtremisDocketMember_169743e8-a4d2-45ef-a47c-7d28f399b785" xlink:href="hsc-20211231.xsd#hsc_PendingLitigationActiveOrInExtremisDocketMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_b32233f2-a08f-4720-83ba-7f54db5216ca" xlink:to="loc_hsc_PendingLitigationActiveOrInExtremisDocketMember_169743e8-a4d2-45ef-a47c-7d28f399b785" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_86c4fc96-8214-4c0b-bb31-021540b1fee0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_fac4003a-409a-48ab-9bcc-6df60099a4fe" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_86c4fc96-8214-4c0b-bb31-021540b1fee0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_86c4fc96-8214-4c0b-bb31-021540b1fee0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_86c4fc96-8214-4c0b-bb31-021540b1fee0" xlink:to="loc_us-gaap_LossContingencyNatureDomain_86c4fc96-8214-4c0b-bb31-021540b1fee0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_9cafd8a0-bf7e-4672-925c-2d2976898304" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_86c4fc96-8214-4c0b-bb31-021540b1fee0" xlink:to="loc_us-gaap_LossContingencyNatureDomain_9cafd8a0-bf7e-4672-925c-2d2976898304" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ValueAddedTaxAssessmentsJanuary2004ToMay2005Member_d039ec84-176d-4aa2-a34f-04c2bdaae34d" xlink:href="hsc-20211231.xsd#hsc_ValueAddedTaxAssessmentsJanuary2004ToMay2005Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_9cafd8a0-bf7e-4672-925c-2d2976898304" xlink:to="loc_hsc_ValueAddedTaxAssessmentsJanuary2004ToMay2005Member_d039ec84-176d-4aa2-a34f-04c2bdaae34d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ValueAddedTaxAssessmentsJanuary2002ToDecember2003Member_a65a2e0e-e5e2-4bd6-8c08-3ec625f97047" xlink:href="hsc-20211231.xsd#hsc_ValueAddedTaxAssessmentsJanuary2002ToDecember2003Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_9cafd8a0-bf7e-4672-925c-2d2976898304" xlink:to="loc_hsc_ValueAddedTaxAssessmentsJanuary2002ToDecember2003Member_a65a2e0e-e5e2-4bd6-8c08-3ec625f97047" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_LosscontingencyBrazilianlaborclaimsMember_63604e07-398c-43d4-a65f-6afb5e99e262" xlink:href="hsc-20211231.xsd#hsc_LosscontingencyBrazilianlaborclaimsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_9cafd8a0-bf7e-4672-925c-2d2976898304" xlink:to="loc_hsc_LosscontingencyBrazilianlaborclaimsMember_63604e07-398c-43d4-a65f-6afb5e99e262" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_OtherIncludingAsbestosRelatedClaimsMember_04498598-f13b-407f-bead-3c2dd87726b8" xlink:href="hsc-20211231.xsd#hsc_OtherIncludingAsbestosRelatedClaimsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_9cafd8a0-bf7e-4672-925c-2d2976898304" xlink:to="loc_hsc_OtherIncludingAsbestosRelatedClaimsMember_04498598-f13b-407f-bead-3c2dd87726b8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_d66d3b4b-c1fe-43d8-a316-265434870bf6" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_fac4003a-409a-48ab-9bcc-6df60099a4fe" xlink:to="loc_srt_RangeAxis_d66d3b4b-c1fe-43d8-a316-265434870bf6" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_d66d3b4b-c1fe-43d8-a316-265434870bf6_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_d66d3b4b-c1fe-43d8-a316-265434870bf6" xlink:to="loc_srt_RangeMember_d66d3b4b-c1fe-43d8-a316-265434870bf6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_0a8b1879-3fec-469a-8e0e-f8a9fdc69f39" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_d66d3b4b-c1fe-43d8-a316-265434870bf6" xlink:to="loc_srt_RangeMember_0a8b1879-3fec-469a-8e0e-f8a9fdc69f39" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_160d80b8-4d5b-4227-8561-f3a87d6f8344" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_0a8b1879-3fec-469a-8e0e-f8a9fdc69f39" xlink:to="loc_srt_MinimumMember_160d80b8-4d5b-4227-8561-f3a87d6f8344" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_fa92653f-f91e-4eee-81d4-59dc11631d7d" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_0a8b1879-3fec-469a-8e0e-f8a9fdc69f39" xlink:to="loc_srt_MaximumMember_fa92653f-f91e-4eee-81d4-59dc11631d7d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipAxis_315b2ea5-8f48-48e8-a3ba-ce95552fe724" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_OwnershipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_fac4003a-409a-48ab-9bcc-6df60099a4fe" xlink:to="loc_srt_OwnershipAxis_315b2ea5-8f48-48e8-a3ba-ce95552fe724" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_315b2ea5-8f48-48e8-a3ba-ce95552fe724_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_OwnershipAxis_315b2ea5-8f48-48e8-a3ba-ce95552fe724" xlink:to="loc_srt_OwnershipDomain_315b2ea5-8f48-48e8-a3ba-ce95552fe724_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_f76edcd1-c6fd-4ab2-ac38-c77f6e074ab1" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_OwnershipAxis_315b2ea5-8f48-48e8-a3ba-ce95552fe724" xlink:to="loc_srt_OwnershipDomain_f76edcd1-c6fd-4ab2-ac38-c77f6e074ab1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_6f60021c-f03c-4785-b7b5-664694443395" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_fac4003a-409a-48ab-9bcc-6df60099a4fe" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_6f60021c-f03c-4785-b7b5-664694443395" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_6f60021c-f03c-4785-b7b5-664694443395_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_6f60021c-f03c-4785-b7b5-664694443395" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_6f60021c-f03c-4785-b7b5-664694443395_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_68acbef9-81d1-42b8-818b-e905ae3a7a0f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_6f60021c-f03c-4785-b7b5-664694443395" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_68acbef9-81d1-42b8-818b-e905ae3a7a0f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_ff24ae5b-01ad-4657-b11e-b12db1d8edf2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_68acbef9-81d1-42b8-818b-e905ae3a7a0f" xlink:to="loc_us-gaap_SubsequentEventMember_ff24ae5b-01ad-4657-b11e-b12db1d8edf2" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/CapitalStockDetails2" xlink:type="simple" xlink:href="hsc-20211231.xsd#CapitalStockDetails2"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/CapitalStockDetails2" xlink:type="extended" id="i9abb993bf3664e639a11481e57c87364_CapitalStockDetails2">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_752e9ded-8332-4dba-90ab-aa2fe3d1d61b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_091276fb-51d4-4a30-95fd-e6fd40fbfd3e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_752e9ded-8332-4dba-90ab-aa2fe3d1d61b" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_091276fb-51d4-4a30-95fd-e6fd40fbfd3e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_dec352fb-ffbe-426c-ad64-95d4fd62fc5e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_091276fb-51d4-4a30-95fd-e6fd40fbfd3e" xlink:to="loc_us-gaap_CommonStockSharesIssued_dec352fb-ffbe-426c-ad64-95d4fd62fc5e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockShares_f4fcd598-6d78-4922-82e4-fcf847d3e967" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TreasuryStockShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_091276fb-51d4-4a30-95fd-e6fd40fbfd3e" xlink:to="loc_us-gaap_TreasuryStockShares_f4fcd598-6d78-4922-82e4-fcf847d3e967" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_fd084b1e-fc3b-4e8d-855f-09060bfc238d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_091276fb-51d4-4a30-95fd-e6fd40fbfd3e" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_fd084b1e-fc3b-4e8d-855f-09060bfc238d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures_ab73fc63-c124-4e7c-a50d-329eb1cad0bc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_091276fb-51d4-4a30-95fd-e6fd40fbfd3e" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures_ab73fc63-c124-4e7c-a50d-329eb1cad0bc" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesOther_45e8af66-5843-4491-8271-bcf22842ff7b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_091276fb-51d4-4a30-95fd-e6fd40fbfd3e" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesOther_45e8af66-5843-4491-8271-bcf22842ff7b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_StockIssuedDuringPeriodStockAppreciationRights_5f9265fb-91ac-4b50-b579-2a1918b32dce" xlink:href="hsc-20211231.xsd#hsc_StockIssuedDuringPeriodStockAppreciationRights"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_091276fb-51d4-4a30-95fd-e6fd40fbfd3e" xlink:to="loc_hsc_StockIssuedDuringPeriodStockAppreciationRights_5f9265fb-91ac-4b50-b579-2a1918b32dce" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_742a5e98-fa36-49dd-963e-42025996ede3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TreasuryStockSharesAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_091276fb-51d4-4a30-95fd-e6fd40fbfd3e" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_742a5e98-fa36-49dd-963e-42025996ede3" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_eaae4208-f894-40b5-a749-0e31a266f3a8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockSharesIssued"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockShares_87f6fb64-d8fd-48e3-82b1-8fea93dc5a3e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TreasuryStockShares"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_43011d2b-ce33-44fe-9c37-a050edb82456" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_4b5eedb7-b4d7-4f20-bac1-0b82e95df951" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_752e9ded-8332-4dba-90ab-aa2fe3d1d61b" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_4b5eedb7-b4d7-4f20-bac1-0b82e95df951" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_67bd1e81-eeb8-4dcb-9e4d-7ed1a8837c4f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_4b5eedb7-b4d7-4f20-bac1-0b82e95df951" xlink:to="loc_us-gaap_StatementClassOfStockAxis_67bd1e81-eeb8-4dcb-9e4d-7ed1a8837c4f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_67bd1e81-eeb8-4dcb-9e4d-7ed1a8837c4f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_67bd1e81-eeb8-4dcb-9e4d-7ed1a8837c4f" xlink:to="loc_us-gaap_ClassOfStockDomain_67bd1e81-eeb8-4dcb-9e4d-7ed1a8837c4f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_94ca9133-5701-4721-9c9b-18035d523ab4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_67bd1e81-eeb8-4dcb-9e4d-7ed1a8837c4f" xlink:to="loc_us-gaap_ClassOfStockDomain_94ca9133-5701-4721-9c9b-18035d523ab4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockMember_e611c3b5-b515-4ca5-bc37-68346ea98639" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TreasuryStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_94ca9133-5701-4721-9c9b-18035d523ab4" xlink:to="loc_us-gaap_TreasuryStockMember_e611c3b5-b515-4ca5-bc37-68346ea98639" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_CommonStockSharesOutstandingMember_71175f58-1f13-40d7-9480-9f7ae991a3e9" xlink:href="hsc-20211231.xsd#hsc_CommonStockSharesOutstandingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_94ca9133-5701-4721-9c9b-18035d523ab4" xlink:to="loc_hsc_CommonStockSharesOutstandingMember_71175f58-1f13-40d7-9480-9f7ae991a3e9" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/CapitalStockDetails3" xlink:type="simple" xlink:href="hsc-20211231.xsd#CapitalStockDetails3"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/CapitalStockDetails3" xlink:type="extended" id="ief4d8ebfd48e4593bf273d62bac57b02_CapitalStockDetails3">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_8c1f0dfc-1d47-4099-961d-c7d65f5b80f8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_1469f106-b609-4268-bfe4-873453e1026f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_8c1f0dfc-1d47-4099-961d-c7d65f5b80f8" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_1469f106-b609-4268-bfe4-873453e1026f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_276af549-1709-40a4-a85a-97cabca01bfc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_8c1f0dfc-1d47-4099-961d-c7d65f5b80f8" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_276af549-1709-40a4-a85a-97cabca01bfc" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_bd50fe1b-e872-4222-8d55-8c9cb28f97a6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_276af549-1709-40a4-a85a-97cabca01bfc" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_bd50fe1b-e872-4222-8d55-8c9cb28f97a6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_bd50fe1b-e872-4222-8d55-8c9cb28f97a6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_bd50fe1b-e872-4222-8d55-8c9cb28f97a6" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_bd50fe1b-e872-4222-8d55-8c9cb28f97a6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_58150702-2751-4c9e-b310-8dd5c960d0ca" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_bd50fe1b-e872-4222-8d55-8c9cb28f97a6" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_58150702-2751-4c9e-b310-8dd5c960d0ca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_a8e7202f-d0df-4a55-a708-220d96a3b741" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_58150702-2751-4c9e-b310-8dd5c960d0ca" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_a8e7202f-d0df-4a55-a708-220d96a3b741" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockAppreciationRightsSARSMember_59c15a24-2c49-4b79-8a18-9ce1b2c01c42" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockAppreciationRightsSARSMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_58150702-2751-4c9e-b310-8dd5c960d0ca" xlink:to="loc_us-gaap_StockAppreciationRightsSARSMember_59c15a24-2c49-4b79-8a18-9ce1b2c01c42" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_12ee97e6-44c4-41b2-b58e-27a04b2c3e37" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_58150702-2751-4c9e-b310-8dd5c960d0ca" xlink:to="loc_us-gaap_PerformanceSharesMember_12ee97e6-44c4-41b2-b58e-27a04b2c3e37" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/StockBasedCompensationTables" xlink:type="simple" xlink:href="hsc-20211231.xsd#StockBasedCompensationTables"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/StockBasedCompensationTables" xlink:type="extended" id="ic5e3a6ceef8249828c97542a2d9a7808_StockBasedCompensationTables">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_aaa1893e-91ba-4645-9c25-38bb5221bc57" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ScheduleOfShareBasedCompensationRestrictedStockUnitsAndCompensationExpenseTableTextBlock_37624339-ff03-447b-b8b4-7dfa14d6d37e" xlink:href="hsc-20211231.xsd#hsc_ScheduleOfShareBasedCompensationRestrictedStockUnitsAndCompensationExpenseTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_aaa1893e-91ba-4645-9c25-38bb5221bc57" xlink:to="loc_hsc_ScheduleOfShareBasedCompensationRestrictedStockUnitsAndCompensationExpenseTableTextBlock_37624339-ff03-447b-b8b4-7dfa14d6d37e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationRestrictedStockUnitsAwardActivityTableTextBlock_58fb4cf4-78f9-403e-a635-649c2ca5667d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationRestrictedStockUnitsAwardActivityTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_aaa1893e-91ba-4645-9c25-38bb5221bc57" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationRestrictedStockUnitsAwardActivityTableTextBlock_58fb4cf4-78f9-403e-a635-649c2ca5667d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ScheduleOfShareBasedPaymentAwardInstrumentsOtherThanOptionsValuationAssumptionsTableTextBlock_f528addf-f6e5-421f-83d5-582b971702c2" xlink:href="hsc-20211231.xsd#hsc_ScheduleOfShareBasedPaymentAwardInstrumentsOtherThanOptionsValuationAssumptionsTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_aaa1893e-91ba-4645-9c25-38bb5221bc57" xlink:to="loc_hsc_ScheduleOfShareBasedPaymentAwardInstrumentsOtherThanOptionsValuationAssumptionsTableTextBlock_f528addf-f6e5-421f-83d5-582b971702c2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationStockAppreciationRightsAwardActivityTableTextBlock_cb11a9ad-fcf6-450f-ab2e-a61f3b3da2de" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationStockAppreciationRightsAwardActivityTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_aaa1893e-91ba-4645-9c25-38bb5221bc57" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationStockAppreciationRightsAwardActivityTableTextBlock_cb11a9ad-fcf6-450f-ab2e-a61f3b3da2de" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockAppreciationRightsByExercisePriceRangeTableTextBlock_238e0583-cc62-45bf-95e7-9515690972dc" xlink:href="hsc-20211231.xsd#hsc_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockAppreciationRightsByExercisePriceRangeTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_aaa1893e-91ba-4645-9c25-38bb5221bc57" xlink:to="loc_hsc_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockAppreciationRightsByExercisePriceRangeTableTextBlock_238e0583-cc62-45bf-95e7-9515690972dc" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfNonvestedShareActivityTableTextBlock_7bdfe038-f41d-4332-b162-aa80c231decc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfNonvestedShareActivityTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_aaa1893e-91ba-4645-9c25-38bb5221bc57" xlink:to="loc_us-gaap_ScheduleOfNonvestedShareActivityTableTextBlock_7bdfe038-f41d-4332-b162-aa80c231decc" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_895ef2c4-6bc4-4142-a139-16d6a99ccfbd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_aaa1893e-91ba-4645-9c25-38bb5221bc57" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_895ef2c4-6bc4-4142-a139-16d6a99ccfbd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_722864e0-b64a-4827-b55c-f48a9080fc55" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_895ef2c4-6bc4-4142-a139-16d6a99ccfbd" xlink:to="loc_us-gaap_AwardTypeAxis_722864e0-b64a-4827-b55c-f48a9080fc55" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_722864e0-b64a-4827-b55c-f48a9080fc55_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_722864e0-b64a-4827-b55c-f48a9080fc55" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_722864e0-b64a-4827-b55c-f48a9080fc55_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_14e29d73-4618-4285-8fd8-5a235e7bcbba" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_722864e0-b64a-4827-b55c-f48a9080fc55" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_14e29d73-4618-4285-8fd8-5a235e7bcbba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockAppreciationRightsSARSMember_9b67b376-240f-4fc8-bdf0-3f86e36ea7ef" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockAppreciationRightsSARSMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_14e29d73-4618-4285-8fd8-5a235e7bcbba" xlink:to="loc_us-gaap_StockAppreciationRightsSARSMember_9b67b376-240f-4fc8-bdf0-3f86e36ea7ef" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_a50505b4-4179-4d4a-8835-6e9350306ca5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_14e29d73-4618-4285-8fd8-5a235e7bcbba" xlink:to="loc_us-gaap_PerformanceSharesMember_a50505b4-4179-4d4a-8835-6e9350306ca5" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/StockBasedCompensationRestrictedStockDetails" xlink:type="simple" xlink:href="hsc-20211231.xsd#StockBasedCompensationRestrictedStockDetails"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/StockBasedCompensationRestrictedStockDetails" xlink:type="extended" id="ic396757136284ec4809a63da4a58fa1e_StockBasedCompensationRestrictedStockDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8027afa8-8b32-4883-aa4f-86398e9d45f5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_9ae3ff3e-c76c-43cc-aab7-0f34b84ff37c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8027afa8-8b32-4883-aa4f-86398e9d45f5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_9ae3ff3e-c76c-43cc-aab7-0f34b84ff37c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_70b47087-ff29-4742-a066-b763d63a9353" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8027afa8-8b32-4883-aa4f-86398e9d45f5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_70b47087-ff29-4742-a066-b763d63a9353" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_046efbb0-a82a-44c1-a3ad-bdfb055df774" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8027afa8-8b32-4883-aa4f-86398e9d45f5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_046efbb0-a82a-44c1-a3ad-bdfb055df774" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_65384d7c-e4d8-4734-9870-b96dc23051f6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8027afa8-8b32-4883-aa4f-86398e9d45f5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_65384d7c-e4d8-4734-9870-b96dc23051f6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_9479e2fa-6ba1-4374-ad64-7648040c3cae" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8027afa8-8b32-4883-aa4f-86398e9d45f5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_9479e2fa-6ba1-4374-ad64-7648040c3cae" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_7a310054-3ab3-487c-b1ce-af58d8322394" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8027afa8-8b32-4883-aa4f-86398e9d45f5" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_7a310054-3ab3-487c-b1ce-af58d8322394" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_006882e8-1037-43a2-851d-ee5c46f87a93" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8027afa8-8b32-4883-aa4f-86398e9d45f5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_006882e8-1037-43a2-851d-ee5c46f87a93" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_aebd9bb0-63fb-4058-8d6f-cf4e83ef6ffa" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_006882e8-1037-43a2-851d-ee5c46f87a93" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_aebd9bb0-63fb-4058-8d6f-cf4e83ef6ffa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_45d19530-7a6e-44d1-8c17-852e1a1e044a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_660b2e30-0264-4815-8b46-7444516c3b05" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_006882e8-1037-43a2-851d-ee5c46f87a93" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_660b2e30-0264-4815-8b46-7444516c3b05" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_5e2c52ab-355e-4a16-8b57-8eb239154535" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_006882e8-1037-43a2-851d-ee5c46f87a93" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_5e2c52ab-355e-4a16-8b57-8eb239154535" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_b225be70-dd93-4f96-93d4-8cfea886c048" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_ccc1136e-f4c8-438d-a114-716285942bfb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8027afa8-8b32-4883-aa4f-86398e9d45f5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_ccc1136e-f4c8-438d-a114-716285942bfb" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_ee363c92-7eb4-483a-9330-a77f084ca686" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_ccc1136e-f4c8-438d-a114-716285942bfb" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_ee363c92-7eb4-483a-9330-a77f084ca686" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_08c99983-8803-4abf-84c5-c5d09bbfe9fe" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_cf47a5aa-f431-4b02-9f47-a67e023630e9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_ccc1136e-f4c8-438d-a114-716285942bfb" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_cf47a5aa-f431-4b02-9f47-a67e023630e9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_5fc877c8-fe5d-448f-bf1b-f71083d5695d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_ccc1136e-f4c8-438d-a114-716285942bfb" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_5fc877c8-fe5d-448f-bf1b-f71083d5695d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_b4ec612a-70c0-44f5-a623-2607467d0919" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAdditionalGeneralDisclosuresAbstract_8dabdcda-40ad-45a0-8364-00fe66705215" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAdditionalGeneralDisclosuresAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8027afa8-8b32-4883-aa4f-86398e9d45f5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAdditionalGeneralDisclosuresAbstract_8dabdcda-40ad-45a0-8364-00fe66705215" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_369ffc5f-2026-4ef2-91de-b9007fe11f56" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAdditionalGeneralDisclosuresAbstract_8dabdcda-40ad-45a0-8364-00fe66705215" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_369ffc5f-2026-4ef2-91de-b9007fe11f56" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_b3b8a329-e503-41fc-ad10-c0f9662ae021" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAdditionalGeneralDisclosuresAbstract_8dabdcda-40ad-45a0-8364-00fe66705215" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_b3b8a329-e503-41fc-ad10-c0f9662ae021" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_d6bb4c70-1fb2-4b81-82ea-343fff904f6b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAdditionalGeneralDisclosuresAbstract_8dabdcda-40ad-45a0-8364-00fe66705215" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_d6bb4c70-1fb2-4b81-82ea-343fff904f6b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentToAdditionalPaidInCapitalIncomeTaxEffectFromShareBasedCompensationNet_c9a10199-7fa5-4bc3-9d39-73fa6bf28c73" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AdjustmentToAdditionalPaidInCapitalIncomeTaxEffectFromShareBasedCompensationNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAdditionalGeneralDisclosuresAbstract_8dabdcda-40ad-45a0-8364-00fe66705215" xlink:to="loc_us-gaap_AdjustmentToAdditionalPaidInCapitalIncomeTaxEffectFromShareBasedCompensationNet_c9a10199-7fa5-4bc3-9d39-73fa6bf28c73" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_b288c407-3772-4399-ac36-8d2b007314ea" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8027afa8-8b32-4883-aa4f-86398e9d45f5" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_b288c407-3772-4399-ac36-8d2b007314ea" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_e62a1880-3005-4da1-97ab-d27a51fd842c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_b288c407-3772-4399-ac36-8d2b007314ea" xlink:to="loc_us-gaap_PlanNameAxis_e62a1880-3005-4da1-97ab-d27a51fd842c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_e62a1880-3005-4da1-97ab-d27a51fd842c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_e62a1880-3005-4da1-97ab-d27a51fd842c" xlink:to="loc_us-gaap_PlanNameDomain_e62a1880-3005-4da1-97ab-d27a51fd842c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_57a2a319-4f11-4d80-a509-c3b02a35961e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_e62a1880-3005-4da1-97ab-d27a51fd842c" xlink:to="loc_us-gaap_PlanNameDomain_57a2a319-4f11-4d80-a509-c3b02a35961e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_EquityAndIncentiveCompensationPlan2013Member_8f947bad-7782-4ea6-8044-8f49edae31e7" xlink:href="hsc-20211231.xsd#hsc_EquityAndIncentiveCompensationPlan2013Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_57a2a319-4f11-4d80-a509-c3b02a35961e" xlink:to="loc_hsc_EquityAndIncentiveCompensationPlan2013Member_8f947bad-7782-4ea6-8044-8f49edae31e7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_NonEmployeeDirectorsStockPlan1995Member_efe9d226-58a1-4b76-bf7c-2775ce33cf74" xlink:href="hsc-20211231.xsd#hsc_NonEmployeeDirectorsStockPlan1995Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_57a2a319-4f11-4d80-a509-c3b02a35961e" xlink:to="loc_hsc_NonEmployeeDirectorsStockPlan1995Member_efe9d226-58a1-4b76-bf7c-2775ce33cf74" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ExecutiveIncentiveCompensationPlan1995Member_efda4a50-b304-4052-8502-87acb448c0ae" xlink:href="hsc-20211231.xsd#hsc_ExecutiveIncentiveCompensationPlan1995Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_57a2a319-4f11-4d80-a509-c3b02a35961e" xlink:to="loc_hsc_ExecutiveIncentiveCompensationPlan1995Member_efda4a50-b304-4052-8502-87acb448c0ae" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_ea77f3b2-6d4e-49c1-9e90-6ae0ccafbc86" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_b288c407-3772-4399-ac36-8d2b007314ea" xlink:to="loc_us-gaap_AwardTypeAxis_ea77f3b2-6d4e-49c1-9e90-6ae0ccafbc86" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_ea77f3b2-6d4e-49c1-9e90-6ae0ccafbc86_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_ea77f3b2-6d4e-49c1-9e90-6ae0ccafbc86" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_ea77f3b2-6d4e-49c1-9e90-6ae0ccafbc86_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_244dfa59-2388-412d-a416-1d3cb76a8f11" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_ea77f3b2-6d4e-49c1-9e90-6ae0ccafbc86" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_244dfa59-2388-412d-a416-1d3cb76a8f11" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_EquityAwardsOtherThanOptionsAndStockAppreciationRightsMember_e191c610-8385-4eaf-a619-60736283bae7" xlink:href="hsc-20211231.xsd#hsc_EquityAwardsOtherThanOptionsAndStockAppreciationRightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_244dfa59-2388-412d-a416-1d3cb76a8f11" xlink:to="loc_hsc_EquityAwardsOtherThanOptionsAndStockAppreciationRightsMember_e191c610-8385-4eaf-a619-60736283bae7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_dc802b49-1ed1-43f5-84b9-7f474b8e50ec" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_244dfa59-2388-412d-a416-1d3cb76a8f11" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_dc802b49-1ed1-43f5-84b9-7f474b8e50ec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardDateAxis_49f354bf-e367-4bee-b0a0-b32ad7c3f4ff" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AwardDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_b288c407-3772-4399-ac36-8d2b007314ea" xlink:to="loc_us-gaap_AwardDateAxis_49f354bf-e367-4bee-b0a0-b32ad7c3f4ff" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardDateDomain_49f354bf-e367-4bee-b0a0-b32ad7c3f4ff_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AwardDateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardDateAxis_49f354bf-e367-4bee-b0a0-b32ad7c3f4ff" xlink:to="loc_us-gaap_AwardDateDomain_49f354bf-e367-4bee-b0a0-b32ad7c3f4ff_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardDateDomain_5d64e82f-f2fe-4c8b-9776-b7a8c888fa06" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AwardDateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardDateAxis_49f354bf-e367-4bee-b0a0-b32ad7c3f4ff" xlink:to="loc_us-gaap_AwardDateDomain_5d64e82f-f2fe-4c8b-9776-b7a8c888fa06" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_IssuePeriod2016Member_b381f9ea-11e0-45bd-b12a-4f6709e31f51" xlink:href="hsc-20211231.xsd#hsc_IssuePeriod2016Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AwardDateDomain_5d64e82f-f2fe-4c8b-9776-b7a8c888fa06" xlink:to="loc_hsc_IssuePeriod2016Member_b381f9ea-11e0-45bd-b12a-4f6709e31f51" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_IssuePeriod2017Member_7d3f1b5d-349c-4d1c-ad30-f2a8f6afa253" xlink:href="hsc-20211231.xsd#hsc_IssuePeriod2017Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AwardDateDomain_5d64e82f-f2fe-4c8b-9776-b7a8c888fa06" xlink:to="loc_hsc_IssuePeriod2017Member_7d3f1b5d-349c-4d1c-ad30-f2a8f6afa253" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_IssuePeriod2018Member_a91db953-396e-4e01-b057-bb0c3e740f61" xlink:href="hsc-20211231.xsd#hsc_IssuePeriod2018Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AwardDateDomain_5d64e82f-f2fe-4c8b-9776-b7a8c888fa06" xlink:to="loc_hsc_IssuePeriod2018Member_a91db953-396e-4e01-b057-bb0c3e740f61" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_IssuePeriod2019Member_432ec1a6-cd84-4d95-adad-63306866f477" xlink:href="hsc-20211231.xsd#hsc_IssuePeriod2019Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AwardDateDomain_5d64e82f-f2fe-4c8b-9776-b7a8c888fa06" xlink:to="loc_hsc_IssuePeriod2019Member_432ec1a6-cd84-4d95-adad-63306866f477" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_IssuePeriod2020Member_574a4412-1c06-4ad2-8c17-8b70fa234d3f" xlink:href="hsc-20211231.xsd#hsc_IssuePeriod2020Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AwardDateDomain_5d64e82f-f2fe-4c8b-9776-b7a8c888fa06" xlink:to="loc_hsc_IssuePeriod2020Member_574a4412-1c06-4ad2-8c17-8b70fa234d3f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_IssuePeriod2021Member_3428884c-06ab-41f9-8474-7ec58adc3d05" xlink:href="hsc-20211231.xsd#hsc_IssuePeriod2021Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AwardDateDomain_5d64e82f-f2fe-4c8b-9776-b7a8c888fa06" xlink:to="loc_hsc_IssuePeriod2021Member_3428884c-06ab-41f9-8474-7ec58adc3d05" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualAxis_08f95a83-c324-424f-812b-7b12d01a28d4" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_TitleOfIndividualAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_b288c407-3772-4399-ac36-8d2b007314ea" xlink:to="loc_srt_TitleOfIndividualAxis_08f95a83-c324-424f-812b-7b12d01a28d4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_08f95a83-c324-424f-812b-7b12d01a28d4_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_TitleOfIndividualAxis_08f95a83-c324-424f-812b-7b12d01a28d4" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_08f95a83-c324-424f-812b-7b12d01a28d4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_d69ee2b3-9c1d-41fc-b2e4-76bfe67cdc60" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_TitleOfIndividualAxis_08f95a83-c324-424f-812b-7b12d01a28d4" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_d69ee2b3-9c1d-41fc-b2e4-76bfe67cdc60" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_OfficersAndKeyEmployeesMember_8161659e-818b-41b9-bd3c-f445ece49a3f" xlink:href="hsc-20211231.xsd#hsc_OfficersAndKeyEmployeesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_d69ee2b3-9c1d-41fc-b2e4-76bfe67cdc60" xlink:to="loc_hsc_OfficersAndKeyEmployeesMember_8161659e-818b-41b9-bd3c-f445ece49a3f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_NonEmployeeDirectorMember_504098a3-4531-4120-b2e8-a8bd846b3c49" xlink:href="hsc-20211231.xsd#hsc_NonEmployeeDirectorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_d69ee2b3-9c1d-41fc-b2e4-76bfe67cdc60" xlink:to="loc_hsc_NonEmployeeDirectorMember_504098a3-4531-4120-b2e8-a8bd846b3c49" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/StockBasedCompensationStockAppreciationRightsDetails" xlink:type="simple" xlink:href="hsc-20211231.xsd#StockBasedCompensationStockAppreciationRightsDetails"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/StockBasedCompensationStockAppreciationRightsDetails" xlink:type="extended" id="ice801ae1c8e84778aa9f065252bea4c5_StockBasedCompensationStockAppreciationRightsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f0f2ff5d-3cc6-4bdc-9e92-b96f0ca37b67" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_d78f031c-7fe9-4b70-a611-e514cf2a13d6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f0f2ff5d-3cc6-4bdc-9e92-b96f0ca37b67" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_d78f031c-7fe9-4b70-a611-e514cf2a13d6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_e98cabd2-a6ed-4e1a-a117-79440ccb4ccf" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f0f2ff5d-3cc6-4bdc-9e92-b96f0ca37b67" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_e98cabd2-a6ed-4e1a-a117-79440ccb4ccf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_6e9cdfda-21e8-4432-b960-a3a1d59dcaa1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f0f2ff5d-3cc6-4bdc-9e92-b96f0ca37b67" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_6e9cdfda-21e8-4432-b960-a3a1d59dcaa1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_a2620c17-7751-4bf5-9416-1c2e3db1434d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_6e9cdfda-21e8-4432-b960-a3a1d59dcaa1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_a2620c17-7751-4bf5-9416-1c2e3db1434d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_c120c11c-233e-43fa-9f37-4f5827846baa" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_6e9cdfda-21e8-4432-b960-a3a1d59dcaa1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_c120c11c-233e-43fa-9f37-4f5827846baa" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_eaac66fb-0914-4949-9e5b-1ec23938fed1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_6e9cdfda-21e8-4432-b960-a3a1d59dcaa1" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_eaac66fb-0914-4949-9e5b-1ec23938fed1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_324b315a-b7c3-47d2-b886-90f62455a5de" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_6e9cdfda-21e8-4432-b960-a3a1d59dcaa1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_324b315a-b7c3-47d2-b886-90f62455a5de" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharePrice_faf05c3f-feb7-414e-aa97-9c070450573b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_6e9cdfda-21e8-4432-b960-a3a1d59dcaa1" xlink:to="loc_us-gaap_SharePrice_faf05c3f-feb7-414e-aa97-9c070450573b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_668817cc-b9a5-4b02-847a-24b74e5ed845" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f0f2ff5d-3cc6-4bdc-9e92-b96f0ca37b67" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_668817cc-b9a5-4b02-847a-24b74e5ed845" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber_84648dcb-e4e7-4fc0-9a7e-c803abb84188" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_668817cc-b9a5-4b02-847a-24b74e5ed845" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber_84648dcb-e4e7-4fc0-9a7e-c803abb84188" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted_0922150e-b337-49b7-9751-8dbc1af6f382" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_668817cc-b9a5-4b02-847a-24b74e5ed845" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted_0922150e-b337-49b7-9751-8dbc1af6f382" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised_44491f95-5b8d-4793-a995-f4dc7512f511" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_668817cc-b9a5-4b02-847a-24b74e5ed845" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised_44491f95-5b8d-4793-a995-f4dc7512f511" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeitures_86d1de8b-78d8-4492-b33d-c60111b62f92" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeitures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_668817cc-b9a5-4b02-847a-24b74e5ed845" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeitures_86d1de8b-78d8-4492-b33d-c60111b62f92" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber_259d2363-f092-47ba-bce6-015e47b6a6e8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageExercisePriceRollForward_a21fa4ab-e360-4ce5-a9f9-a3edcc8eb457" xlink:href="hsc-20211231.xsd#hsc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageExercisePriceRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f0f2ff5d-3cc6-4bdc-9e92-b96f0ca37b67" xlink:to="loc_hsc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageExercisePriceRollForward_a21fa4ab-e360-4ce5-a9f9-a3edcc8eb457" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageExercisePrice_1c1bce1d-3fa1-4fb3-af54-12e838bf7d26" xlink:href="hsc-20211231.xsd#hsc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hsc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageExercisePriceRollForward_a21fa4ab-e360-4ce5-a9f9-a3edcc8eb457" xlink:to="loc_hsc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageExercisePrice_1c1bce1d-3fa1-4fb3-af54-12e838bf7d26" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageExercisePrice_632ae9ad-0c2a-4921-9d1c-1677999629e0" xlink:href="hsc-20211231.xsd#hsc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hsc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageExercisePriceRollForward_a21fa4ab-e360-4ce5-a9f9-a3edcc8eb457" xlink:to="loc_hsc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageExercisePrice_632ae9ad-0c2a-4921-9d1c-1677999629e0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsExercisedinPeriodWeightedAverageExercisePrice_2826e7d1-1e79-4afc-a6aa-d6cb0566e916" xlink:href="hsc-20211231.xsd#hsc_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsExercisedinPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hsc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageExercisePriceRollForward_a21fa4ab-e360-4ce5-a9f9-a3edcc8eb457" xlink:to="loc_hsc_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsExercisedinPeriodWeightedAverageExercisePrice_2826e7d1-1e79-4afc-a6aa-d6cb0566e916" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriodWeightedAverageExercisePrice_c4c29cd9-e319-4185-b122-39b96ca82a4b" xlink:href="hsc-20211231.xsd#hsc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_hsc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageExercisePriceRollForward_a21fa4ab-e360-4ce5-a9f9-a3edcc8eb457" xlink:to="loc_hsc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriodWeightedAverageExercisePrice_c4c29cd9-e319-4185-b122-39b96ca82a4b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageExercisePrice_112cb689-3fd9-4a28-8d01-dfac87c7e7f3" xlink:href="hsc-20211231.xsd#hsc_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageExercisePrice"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueOutstanding_5f3c2e41-5c1d-4367-bc0e-c1ce245ec759" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f0f2ff5d-3cc6-4bdc-9e92-b96f0ca37b67" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueOutstanding_5f3c2e41-5c1d-4367-bc0e-c1ce245ec759" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsAggregateIntrinsicValueExercised_5d32703d-0dd6-4b12-a287-cc46b68d5ffc" xlink:href="hsc-20211231.xsd#hsc_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsAggregateIntrinsicValueExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f0f2ff5d-3cc6-4bdc-9e92-b96f0ca37b67" xlink:to="loc_hsc_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsAggregateIntrinsicValueExercised_5d32703d-0dd6-4b12-a287-cc46b68d5ffc" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit_6ee1136b-f34d-4f26-aebb-df5364144093" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f0f2ff5d-3cc6-4bdc-9e92-b96f0ca37b67" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit_6ee1136b-f34d-4f26-aebb-df5364144093" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit_6f3b4d90-1fb2-4cf8-848d-4345f1757989" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f0f2ff5d-3cc6-4bdc-9e92-b96f0ca37b67" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit_6f3b4d90-1fb2-4cf8-848d-4345f1757989" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_SharebasedCompensationSharesAuthorizedUnderStockAppreciationRightsExercisePriceRangeNumberOfVestedShares_c9c7bc32-bf7c-4346-b849-870052bc6924" xlink:href="hsc-20211231.xsd#hsc_SharebasedCompensationSharesAuthorizedUnderStockAppreciationRightsExercisePriceRangeNumberOfVestedShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f0f2ff5d-3cc6-4bdc-9e92-b96f0ca37b67" xlink:to="loc_hsc_SharebasedCompensationSharesAuthorizedUnderStockAppreciationRightsExercisePriceRangeNumberOfVestedShares_c9c7bc32-bf7c-4346-b849-870052bc6924" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_SharebasedCompensationSharesAuthorizedUnderStockAppreciationRightsExercisePriceRangeNumberOfUnvestedShares_5f66f1e4-d563-49a5-8e8b-cddf86df4d19" xlink:href="hsc-20211231.xsd#hsc_SharebasedCompensationSharesAuthorizedUnderStockAppreciationRightsExercisePriceRangeNumberOfUnvestedShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f0f2ff5d-3cc6-4bdc-9e92-b96f0ca37b67" xlink:to="loc_hsc_SharebasedCompensationSharesAuthorizedUnderStockAppreciationRightsExercisePriceRangeNumberOfUnvestedShares_5f66f1e4-d563-49a5-8e8b-cddf86df4d19" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ShareBasedCompensationSharesAuthorizedUnderStockAppreciationRightsExercisePriceRangeOutstandingSARsWeightedAverageExercisePrice_d8972ec9-3a61-43d4-a2f8-4c6068acca60" xlink:href="hsc-20211231.xsd#hsc_ShareBasedCompensationSharesAuthorizedUnderStockAppreciationRightsExercisePriceRangeOutstandingSARsWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f0f2ff5d-3cc6-4bdc-9e92-b96f0ca37b67" xlink:to="loc_hsc_ShareBasedCompensationSharesAuthorizedUnderStockAppreciationRightsExercisePriceRangeOutstandingSARsWeightedAverageExercisePrice_d8972ec9-3a61-43d4-a2f8-4c6068acca60" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ShareBasedCompensationSharesAuthorizedUnderStockAppreciationRightsExercisePriceRangeOutstandingSARsWeightedAverageRemainingContractualTerm_a183c1bd-d915-4f54-9f0d-d22426b2d864" xlink:href="hsc-20211231.xsd#hsc_ShareBasedCompensationSharesAuthorizedUnderStockAppreciationRightsExercisePriceRangeOutstandingSARsWeightedAverageRemainingContractualTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f0f2ff5d-3cc6-4bdc-9e92-b96f0ca37b67" xlink:to="loc_hsc_ShareBasedCompensationSharesAuthorizedUnderStockAppreciationRightsExercisePriceRangeOutstandingSARsWeightedAverageRemainingContractualTerm_a183c1bd-d915-4f54-9f0d-d22426b2d864" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ShareBasedCompensationSharesAuthorizedUnderStockAppreciationRightsExercisePriceRangeNumberOfExercisableShares_dd0edf2a-0e87-419d-947f-260841d3fef1" xlink:href="hsc-20211231.xsd#hsc_ShareBasedCompensationSharesAuthorizedUnderStockAppreciationRightsExercisePriceRangeNumberOfExercisableShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f0f2ff5d-3cc6-4bdc-9e92-b96f0ca37b67" xlink:to="loc_hsc_ShareBasedCompensationSharesAuthorizedUnderStockAppreciationRightsExercisePriceRangeNumberOfExercisableShares_dd0edf2a-0e87-419d-947f-260841d3fef1" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ShareBasedCompensationSharesAuthorizedUnderStockAppreciationRightsExercisePriceRangeExercisableSARsWeightedAverageExercisePrice_da60b200-490f-473a-b339-e480844698bd" xlink:href="hsc-20211231.xsd#hsc_ShareBasedCompensationSharesAuthorizedUnderStockAppreciationRightsExercisePriceRangeExercisableSARsWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f0f2ff5d-3cc6-4bdc-9e92-b96f0ca37b67" xlink:to="loc_hsc_ShareBasedCompensationSharesAuthorizedUnderStockAppreciationRightsExercisePriceRangeExercisableSARsWeightedAverageExercisePrice_da60b200-490f-473a-b339-e480844698bd" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_8366028f-f7ff-47da-9036-6df867c8deab" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f0f2ff5d-3cc6-4bdc-9e92-b96f0ca37b67" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_8366028f-f7ff-47da-9036-6df867c8deab" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_9d46f7a2-56da-4283-8c25-ad17c0df1442" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f0f2ff5d-3cc6-4bdc-9e92-b96f0ca37b67" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_9d46f7a2-56da-4283-8c25-ad17c0df1442" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_382c3211-ae50-4a50-a9ef-d77772ecd9b6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f0f2ff5d-3cc6-4bdc-9e92-b96f0ca37b67" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_382c3211-ae50-4a50-a9ef-d77772ecd9b6" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_718c73b0-bb2e-4e0c-ae02-624e72eec899" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f0f2ff5d-3cc6-4bdc-9e92-b96f0ca37b67" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_718c73b0-bb2e-4e0c-ae02-624e72eec899" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_6165eb7c-04b2-472b-9729-7ca58108176c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_718c73b0-bb2e-4e0c-ae02-624e72eec899" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_6165eb7c-04b2-472b-9729-7ca58108176c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_b1acbf98-0107-4d40-adf3-325728d0c069" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_718c73b0-bb2e-4e0c-ae02-624e72eec899" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_b1acbf98-0107-4d40-adf3-325728d0c069" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_a312902a-55df-4ec8-86ad-a17a6857172d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_718c73b0-bb2e-4e0c-ae02-624e72eec899" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_a312902a-55df-4ec8-86ad-a17a6857172d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_bb775752-5f28-4954-b83b-63c4c1cd4481" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_718c73b0-bb2e-4e0c-ae02-624e72eec899" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_bb775752-5f28-4954-b83b-63c4c1cd4481" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_7bdfe890-069a-417a-a35d-a126ac6bb967" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_9d8e991e-ac86-4a70-b3fc-3afecbbeebec" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f0f2ff5d-3cc6-4bdc-9e92-b96f0ca37b67" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_9d8e991e-ac86-4a70-b3fc-3afecbbeebec" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_6aab3149-f7e6-40d4-9a5e-c32c22f5266e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_9d8e991e-ac86-4a70-b3fc-3afecbbeebec" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_6aab3149-f7e6-40d4-9a5e-c32c22f5266e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_070c3531-7694-40ca-a8e2-523affbb1d61" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_9d8e991e-ac86-4a70-b3fc-3afecbbeebec" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_070c3531-7694-40ca-a8e2-523affbb1d61" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_86cefcaa-4e3d-40c7-b217-9b5ba812e0f1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_9d8e991e-ac86-4a70-b3fc-3afecbbeebec" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_86cefcaa-4e3d-40c7-b217-9b5ba812e0f1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_cff84adf-9786-4962-a38b-06f8a08067d8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_9d8e991e-ac86-4a70-b3fc-3afecbbeebec" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_cff84adf-9786-4962-a38b-06f8a08067d8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_1b7fa1eb-1e2b-415e-89be-7777aaa41fee" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_880ce62b-aadc-4880-8663-45e379b83d25" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f0f2ff5d-3cc6-4bdc-9e92-b96f0ca37b67" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_880ce62b-aadc-4880-8663-45e379b83d25" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_13dec4f3-f1a3-427a-8bb6-5f6efc01f555" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_880ce62b-aadc-4880-8663-45e379b83d25" xlink:to="loc_us-gaap_PlanNameAxis_13dec4f3-f1a3-427a-8bb6-5f6efc01f555" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_13dec4f3-f1a3-427a-8bb6-5f6efc01f555_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_13dec4f3-f1a3-427a-8bb6-5f6efc01f555" xlink:to="loc_us-gaap_PlanNameDomain_13dec4f3-f1a3-427a-8bb6-5f6efc01f555_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_53a07447-a278-47ae-9322-b5db24d96596" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_13dec4f3-f1a3-427a-8bb6-5f6efc01f555" xlink:to="loc_us-gaap_PlanNameDomain_53a07447-a278-47ae-9322-b5db24d96596" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_EquityAndIncentiveCompensationPlan2013Member_d5a6af5c-2196-4c69-b7b7-96ff28ca3ef8" xlink:href="hsc-20211231.xsd#hsc_EquityAndIncentiveCompensationPlan2013Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_53a07447-a278-47ae-9322-b5db24d96596" xlink:to="loc_hsc_EquityAndIncentiveCompensationPlan2013Member_d5a6af5c-2196-4c69-b7b7-96ff28ca3ef8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_270a7d9b-3668-43c5-954d-d4242d3de3b5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_880ce62b-aadc-4880-8663-45e379b83d25" xlink:to="loc_us-gaap_AwardTypeAxis_270a7d9b-3668-43c5-954d-d4242d3de3b5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_270a7d9b-3668-43c5-954d-d4242d3de3b5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_270a7d9b-3668-43c5-954d-d4242d3de3b5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_270a7d9b-3668-43c5-954d-d4242d3de3b5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_ddf9358e-c493-46f4-b77b-436180c32ece" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_270a7d9b-3668-43c5-954d-d4242d3de3b5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_ddf9358e-c493-46f4-b77b-436180c32ece" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockAppreciationRightsSARSMember_0a35a7a9-06f9-4a49-b647-fad718a41b82" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockAppreciationRightsSARSMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_ddf9358e-c493-46f4-b77b-436180c32ece" xlink:to="loc_us-gaap_StockAppreciationRightsSARSMember_0a35a7a9-06f9-4a49-b647-fad718a41b82" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_46f54f50-6794-4bdc-af87-5bec8c1b74c3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_880ce62b-aadc-4880-8663-45e379b83d25" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_46f54f50-6794-4bdc-af87-5bec8c1b74c3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_46f54f50-6794-4bdc-af87-5bec8c1b74c3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_46f54f50-6794-4bdc-af87-5bec8c1b74c3" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_46f54f50-6794-4bdc-af87-5bec8c1b74c3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_1c47a28e-5d47-4381-b6f3-c3ea18c4cfac" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_46f54f50-6794-4bdc-af87-5bec8c1b74c3" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_1c47a28e-5d47-4381-b6f3-c3ea18c4cfac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ExercisePriceRangeFourMember_d6e8c0de-60ce-4c86-b7a7-fed6bb057eb9" xlink:href="hsc-20211231.xsd#hsc_ExercisePriceRangeFourMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_1c47a28e-5d47-4381-b6f3-c3ea18c4cfac" xlink:to="loc_hsc_ExercisePriceRangeFourMember_d6e8c0de-60ce-4c86-b7a7-fed6bb057eb9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ExercisePriceRangeFiveMember_d1837f8b-42a8-4cf5-9c7f-1d27d9076683" xlink:href="hsc-20211231.xsd#hsc_ExercisePriceRangeFiveMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_1c47a28e-5d47-4381-b6f3-c3ea18c4cfac" xlink:to="loc_hsc_ExercisePriceRangeFiveMember_d1837f8b-42a8-4cf5-9c7f-1d27d9076683" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ExercisePriceRangeSixMember_ad357423-f287-46ca-8edb-53083a9f4515" xlink:href="hsc-20211231.xsd#hsc_ExercisePriceRangeSixMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_1c47a28e-5d47-4381-b6f3-c3ea18c4cfac" xlink:to="loc_hsc_ExercisePriceRangeSixMember_ad357423-f287-46ca-8edb-53083a9f4515" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_9a001e3f-17ba-456f-8cc9-af240f30aac4" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_880ce62b-aadc-4880-8663-45e379b83d25" xlink:to="loc_srt_RangeAxis_9a001e3f-17ba-456f-8cc9-af240f30aac4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_9a001e3f-17ba-456f-8cc9-af240f30aac4_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_9a001e3f-17ba-456f-8cc9-af240f30aac4" xlink:to="loc_srt_RangeMember_9a001e3f-17ba-456f-8cc9-af240f30aac4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_a17b1620-02a8-443f-bf8e-b4ff980d7a15" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_9a001e3f-17ba-456f-8cc9-af240f30aac4" xlink:to="loc_srt_RangeMember_a17b1620-02a8-443f-bf8e-b4ff980d7a15" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_b5f89ba3-c8a1-4801-946a-4144ce66393d" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_a17b1620-02a8-443f-bf8e-b4ff980d7a15" xlink:to="loc_srt_MinimumMember_b5f89ba3-c8a1-4801-946a-4144ce66393d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_188636a4-f70e-4d57-89f5-0142d0e894d6" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_a17b1620-02a8-443f-bf8e-b4ff980d7a15" xlink:to="loc_srt_MaximumMember_188636a4-f70e-4d57-89f5-0142d0e894d6" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/StockBasedCompensationPerformanceStockUnitsDetails" xlink:type="simple" xlink:href="hsc-20211231.xsd#StockBasedCompensationPerformanceStockUnitsDetails"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/StockBasedCompensationPerformanceStockUnitsDetails" xlink:type="extended" id="i70135eef24fb4fd19d9c2fccac06bae1_StockBasedCompensationPerformanceStockUnitsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ca67f4e2-7a7a-407d-8b20-86a8e1469f6c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ShareBasedCompensationArrangementByShareBasedPaymentAwardPerformancePeriod_2ed38b27-a6ff-442a-8974-56a0d88bbcfd" xlink:href="hsc-20211231.xsd#hsc_ShareBasedCompensationArrangementByShareBasedPaymentAwardPerformancePeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ca67f4e2-7a7a-407d-8b20-86a8e1469f6c" xlink:to="loc_hsc_ShareBasedCompensationArrangementByShareBasedPaymentAwardPerformancePeriod_2ed38b27-a6ff-442a-8974-56a0d88bbcfd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ShareBasedCompensationArrangementsByShareBasedPaymentAwardPerformanceStockPayoutPercentageOfInitialGrant_0f5021a5-7107-448c-a476-97f0f570a1e9" xlink:href="hsc-20211231.xsd#hsc_ShareBasedCompensationArrangementsByShareBasedPaymentAwardPerformanceStockPayoutPercentageOfInitialGrant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ca67f4e2-7a7a-407d-8b20-86a8e1469f6c" xlink:to="loc_hsc_ShareBasedCompensationArrangementsByShareBasedPaymentAwardPerformanceStockPayoutPercentageOfInitialGrant_0f5021a5-7107-448c-a476-97f0f570a1e9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_925720e3-e96d-4ccd-aa70-f779dd1856c9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ca67f4e2-7a7a-407d-8b20-86a8e1469f6c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_925720e3-e96d-4ccd-aa70-f779dd1856c9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_9c21bfcc-b465-4a57-820e-654d31073f04" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_925720e3-e96d-4ccd-aa70-f779dd1856c9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_9c21bfcc-b465-4a57-820e-654d31073f04" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_bbe19ef0-a9eb-4caa-95bd-ad1cf5e9f051" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_925720e3-e96d-4ccd-aa70-f779dd1856c9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_bbe19ef0-a9eb-4caa-95bd-ad1cf5e9f051" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_fea12ec9-c1de-4e5e-8157-5c6a53ec949a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_925720e3-e96d-4ccd-aa70-f779dd1856c9" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_fea12ec9-c1de-4e5e-8157-5c6a53ec949a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsWeightedAverageVolatilityRate_487c2b24-11b7-418a-87d3-b556cbc384a4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsWeightedAverageVolatilityRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_925720e3-e96d-4ccd-aa70-f779dd1856c9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsWeightedAverageVolatilityRate_487c2b24-11b7-418a-87d3-b556cbc384a4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_d0e9237d-8742-4029-8de4-ecbcf11643f8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsAndMethodologyAbstract_925720e3-e96d-4ccd-aa70-f779dd1856c9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_d0e9237d-8742-4029-8de4-ecbcf11643f8" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_07036f2f-fbff-4478-b966-777a4f6f1e97" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ca67f4e2-7a7a-407d-8b20-86a8e1469f6c" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_07036f2f-fbff-4478-b966-777a4f6f1e97" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_6da09fb2-dbec-4c44-8590-ae500aab3ced" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ca67f4e2-7a7a-407d-8b20-86a8e1469f6c" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_6da09fb2-dbec-4c44-8590-ae500aab3ced" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_10a903b2-0b17-4339-9c1e-7c72f887fdda" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ca67f4e2-7a7a-407d-8b20-86a8e1469f6c" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_10a903b2-0b17-4339-9c1e-7c72f887fdda" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_4cb00ae4-e2c1-4ac5-96b4-ee448df2fc55" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ca67f4e2-7a7a-407d-8b20-86a8e1469f6c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_4cb00ae4-e2c1-4ac5-96b4-ee448df2fc55" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_d82b5a6d-8341-4f9c-a8cc-9f3e3a97dd18" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_4cb00ae4-e2c1-4ac5-96b4-ee448df2fc55" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_d82b5a6d-8341-4f9c-a8cc-9f3e3a97dd18" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_32916b14-9761-4519-beef-d69ad603ac8e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_4cb00ae4-e2c1-4ac5-96b4-ee448df2fc55" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_32916b14-9761-4519-beef-d69ad603ac8e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_d4479830-bc98-4930-8d5a-478ad97e1083" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_4cb00ae4-e2c1-4ac5-96b4-ee448df2fc55" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_d4479830-bc98-4930-8d5a-478ad97e1083" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeitures_e4000603-698f-4db5-85a9-99613316a8d2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeitures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_4cb00ae4-e2c1-4ac5-96b4-ee448df2fc55" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeitures_e4000603-698f-4db5-85a9-99613316a8d2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_2e4f1d18-9d51-499c-94a4-f2d34b5ab1b4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_4cb00ae4-e2c1-4ac5-96b4-ee448df2fc55" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_2e4f1d18-9d51-499c-94a4-f2d34b5ab1b4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_60f562ac-c560-4b21-853e-789091913975" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_c9400662-2a0e-47dd-a26b-1b8c53ba08e5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ca67f4e2-7a7a-407d-8b20-86a8e1469f6c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_c9400662-2a0e-47dd-a26b-1b8c53ba08e5" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_3d03cec8-e0ef-4f3c-b99d-519744e84ea4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_c9400662-2a0e-47dd-a26b-1b8c53ba08e5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_3d03cec8-e0ef-4f3c-b99d-519744e84ea4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_047abdc9-9e96-453a-9f20-0ebb22e6699e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_eccfeead-77ec-4a47-9076-507711bf8e00" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_c9400662-2a0e-47dd-a26b-1b8c53ba08e5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_eccfeead-77ec-4a47-9076-507711bf8e00" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_6fedcec0-b3ec-4c92-af24-52ce85665e4a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_c9400662-2a0e-47dd-a26b-1b8c53ba08e5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_6fedcec0-b3ec-4c92-af24-52ce85665e4a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_fd7b3b60-4a07-4f82-8327-e391e2b45108" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_f35d50a6-7c40-463e-b1b4-4f9086d9204c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ca67f4e2-7a7a-407d-8b20-86a8e1469f6c" xlink:to="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_f35d50a6-7c40-463e-b1b4-4f9086d9204c" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_03d054c2-5ed4-4eb9-838d-476af3306e28" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ca67f4e2-7a7a-407d-8b20-86a8e1469f6c" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_03d054c2-5ed4-4eb9-838d-476af3306e28" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_dc1440e3-dc5c-4c4b-aa1b-6ada5d2bacab" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_03d054c2-5ed4-4eb9-838d-476af3306e28" xlink:to="loc_us-gaap_AwardTypeAxis_dc1440e3-dc5c-4c4b-aa1b-6ada5d2bacab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_dc1440e3-dc5c-4c4b-aa1b-6ada5d2bacab_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_dc1440e3-dc5c-4c4b-aa1b-6ada5d2bacab" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_dc1440e3-dc5c-4c4b-aa1b-6ada5d2bacab_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_45381d99-927a-41e3-b2aa-237ed3192795" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_dc1440e3-dc5c-4c4b-aa1b-6ada5d2bacab" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_45381d99-927a-41e3-b2aa-237ed3192795" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_2e881434-ae79-4ce6-8013-622be14e26d1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_45381d99-927a-41e3-b2aa-237ed3192795" xlink:to="loc_us-gaap_PerformanceSharesMember_2e881434-ae79-4ce6-8013-622be14e26d1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_6c39a05c-01e6-4163-89fe-132ebb5d5906" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_03d054c2-5ed4-4eb9-838d-476af3306e28" xlink:to="loc_srt_RangeAxis_6c39a05c-01e6-4163-89fe-132ebb5d5906" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_6c39a05c-01e6-4163-89fe-132ebb5d5906_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_6c39a05c-01e6-4163-89fe-132ebb5d5906" xlink:to="loc_srt_RangeMember_6c39a05c-01e6-4163-89fe-132ebb5d5906_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_18c67c56-1bde-4725-b25b-3f26f99d94cf" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_6c39a05c-01e6-4163-89fe-132ebb5d5906" xlink:to="loc_srt_RangeMember_18c67c56-1bde-4725-b25b-3f26f99d94cf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_5b8d94f2-5fa6-4163-967a-bbe538c0a27c" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_18c67c56-1bde-4725-b25b-3f26f99d94cf" xlink:to="loc_srt_MinimumMember_5b8d94f2-5fa6-4163-967a-bbe538c0a27c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_9a2315a7-2e63-46aa-b56a-6fdfe14ec431" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_18c67c56-1bde-4725-b25b-3f26f99d94cf" xlink:to="loc_srt_MaximumMember_9a2315a7-2e63-46aa-b56a-6fdfe14ec431" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/FinancialInstrumentsNarrativeDetails" xlink:type="simple" xlink:href="hsc-20211231.xsd#FinancialInstrumentsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/FinancialInstrumentsNarrativeDetails" xlink:type="extended" id="i8ddf964c74de42a79ee90e5e5ba6fb3a_FinancialInstrumentsNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsLineItems_94e98402-cbe0-4714-b0bd-fa5b02c06c9b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GuaranteeObligationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureOffbalanceSheetRisksFaceAmountLiability_3d1b9961-a132-43c1-8e12-acea58bd1036" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueDisclosureOffbalanceSheetRisksFaceAmountLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_94e98402-cbe0-4714-b0bd-fa5b02c06c9b" xlink:to="loc_us-gaap_FairValueDisclosureOffbalanceSheetRisksFaceAmountLiability_3d1b9961-a132-43c1-8e12-acea58bd1036" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_GuaranteeObligationsTerm1_3747ebc6-b6eb-4930-a87c-20a87677205c" xlink:href="hsc-20211231.xsd#hsc_GuaranteeObligationsTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_94e98402-cbe0-4714-b0bd-fa5b02c06c9b" xlink:to="loc_hsc_GuaranteeObligationsTerm1_3747ebc6-b6eb-4930-a87c-20a87677205c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_GuaranteeObligationsAnnualFeePercentage_7383df04-81c5-4620-804f-c77ae9ea7b88" xlink:href="hsc-20211231.xsd#hsc_GuaranteeObligationsAnnualFeePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_94e98402-cbe0-4714-b0bd-fa5b02c06c9b" xlink:to="loc_hsc_GuaranteeObligationsAnnualFeePercentage_7383df04-81c5-4620-804f-c77ae9ea7b88" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_NumberOfCountriesInWhichEntityHasCurrencyExposures_360b3cad-2018-4e72-b9d6-7484051245f1" xlink:href="hsc-20211231.xsd#hsc_NumberOfCountriesInWhichEntityHasCurrencyExposures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_94e98402-cbe0-4714-b0bd-fa5b02c06c9b" xlink:to="loc_hsc_NumberOfCountriesInWhichEntityHasCurrencyExposures_360b3cad-2018-4e72-b9d6-7484051245f1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsCurrentCarryingValue_92b037c0-99d2-4677-8a92-4574a4a46947" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GuaranteeObligationsCurrentCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_94e98402-cbe0-4714-b0bd-fa5b02c06c9b" xlink:to="loc_us-gaap_GuaranteeObligationsCurrentCarryingValue_92b037c0-99d2-4677-8a92-4574a4a46947" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DerivativesLiabilityResultedFromNettingArrangement_e32fdece-d073-4042-9e11-78431f61de9d" xlink:href="hsc-20211231.xsd#hsc_DerivativesLiabilityResultedFromNettingArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_94e98402-cbe0-4714-b0bd-fa5b02c06c9b" xlink:to="loc_hsc_DerivativesLiabilityResultedFromNettingArrangement_e32fdece-d073-4042-9e11-78431f61de9d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_29d6d4e3-4a3b-4a19-ae13-cf0a2e1c8d8d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_94e98402-cbe0-4714-b0bd-fa5b02c06c9b" xlink:to="loc_us-gaap_DerivativeNotionalAmount_29d6d4e3-4a3b-4a19-ae13-cf0a2e1c8d8d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TranslationAdjustmentForNetInvestmentHedgeIncreaseDecreaseNetOfTax_2a16b05d-6057-4fcc-afae-7194467be4af" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TranslationAdjustmentForNetInvestmentHedgeIncreaseDecreaseNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_94e98402-cbe0-4714-b0bd-fa5b02c06c9b" xlink:to="loc_us-gaap_TranslationAdjustmentForNetInvestmentHedgeIncreaseDecreaseNetOfTax_2a16b05d-6057-4fcc-afae-7194467be4af" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_0da26121-4ed5-4a35-a165-4da5c5261a1f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_94e98402-cbe0-4714-b0bd-fa5b02c06c9b" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_0da26121-4ed5-4a35-a165-4da5c5261a1f" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_98ddf036-e14f-45c7-a81e-7e8ffbd44ef0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_94e98402-cbe0-4714-b0bd-fa5b02c06c9b" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_98ddf036-e14f-45c7-a81e-7e8ffbd44ef0" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfLongTermLinesOfCredit_efaedf8f-defa-4529-9dfe-9d24a7748768" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RepaymentsOfLongTermLinesOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_94e98402-cbe0-4714-b0bd-fa5b02c06c9b" xlink:to="loc_us-gaap_RepaymentsOfLongTermLinesOfCredit_efaedf8f-defa-4529-9dfe-9d24a7748768" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnDiscontinuationOfCashFlowHedgeDueToForecastedTransactionProbableOfNotOccurringNet_0adaf698-5480-42d7-9c6d-d0e2dcbb7ba2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GainLossOnDiscontinuationOfCashFlowHedgeDueToForecastedTransactionProbableOfNotOccurringNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_94e98402-cbe0-4714-b0bd-fa5b02c06c9b" xlink:to="loc_us-gaap_GainLossOnDiscontinuationOfCashFlowHedgeDueToForecastedTransactionProbableOfNotOccurringNet_0adaf698-5480-42d7-9c6d-d0e2dcbb7ba2" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtFairValue_85db0559-402d-4283-b7ad-e0d276bf61e2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermDebtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_94e98402-cbe0-4714-b0bd-fa5b02c06c9b" xlink:to="loc_us-gaap_LongTermDebtFairValue_85db0559-402d-4283-b7ad-e0d276bf61e2" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_2c37ee72-fefd-45cb-8edc-8d37ba43725e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_94e98402-cbe0-4714-b0bd-fa5b02c06c9b" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_2c37ee72-fefd-45cb-8edc-8d37ba43725e" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGuaranteeObligationsTable_9a396af2-1f36-471f-bd58-019e3d69c0d7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfGuaranteeObligationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GuaranteeObligationsLineItems_94e98402-cbe0-4714-b0bd-fa5b02c06c9b" xlink:to="loc_us-gaap_ScheduleOfGuaranteeObligationsTable_9a396af2-1f36-471f-bd58-019e3d69c0d7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_3c8abc70-358e-4706-9ee2-0f7ce5dcbc97" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGuaranteeObligationsTable_9a396af2-1f36-471f-bd58-019e3d69c0d7" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_3c8abc70-358e-4706-9ee2-0f7ce5dcbc97" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_3c8abc70-358e-4706-9ee2-0f7ce5dcbc97_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_3c8abc70-358e-4706-9ee2-0f7ce5dcbc97" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_3c8abc70-358e-4706-9ee2-0f7ce5dcbc97_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_e4304172-8300-4b81-9bb6-4351af5c6abf" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_3c8abc70-358e-4706-9ee2-0f7ce5dcbc97" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_e4304172-8300-4b81-9bb6-4351af5c6abf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationMember_f2ab002b-34fd-4aab-be54-836689070446" xlink:href="hsc-20211231.xsd#hsc_DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_e4304172-8300-4b81-9bb6-4351af5c6abf" xlink:to="loc_hsc_DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationMember_f2ab002b-34fd-4aab-be54-836689070446" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtConversionByUniqueDescriptionAxis_75fd8880-1df5-4522-a580-ffbbb7a2cbed" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtConversionByUniqueDescriptionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGuaranteeObligationsTable_9a396af2-1f36-471f-bd58-019e3d69c0d7" xlink:to="loc_us-gaap_DebtConversionByUniqueDescriptionAxis_75fd8880-1df5-4522-a580-ffbbb7a2cbed" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtConversionNameDomain_75fd8880-1df5-4522-a580-ffbbb7a2cbed_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtConversionNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtConversionByUniqueDescriptionAxis_75fd8880-1df5-4522-a580-ffbbb7a2cbed" xlink:to="loc_us-gaap_DebtConversionNameDomain_75fd8880-1df5-4522-a580-ffbbb7a2cbed_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtConversionNameDomain_3a0aa5ba-f8ec-4918-8900-607ce6bd9352" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtConversionNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtConversionByUniqueDescriptionAxis_75fd8880-1df5-4522-a580-ffbbb7a2cbed" xlink:to="loc_us-gaap_DebtConversionNameDomain_3a0aa5ba-f8ec-4918-8900-607ce6bd9352" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsByNatureAxis_f574802e-0cbb-4893-93c5-3eaba97c87a7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GuaranteeObligationsByNatureAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGuaranteeObligationsTable_9a396af2-1f36-471f-bd58-019e3d69c0d7" xlink:to="loc_us-gaap_GuaranteeObligationsByNatureAxis_f574802e-0cbb-4893-93c5-3eaba97c87a7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsNatureDomain_f574802e-0cbb-4893-93c5-3eaba97c87a7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GuaranteeObligationsNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_GuaranteeObligationsByNatureAxis_f574802e-0cbb-4893-93c5-3eaba97c87a7" xlink:to="loc_us-gaap_GuaranteeObligationsNatureDomain_f574802e-0cbb-4893-93c5-3eaba97c87a7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsNatureDomain_d7b8a5b0-2d0b-4dfe-a2f6-b78a3b74ebf8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GuaranteeObligationsNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_GuaranteeObligationsByNatureAxis_f574802e-0cbb-4893-93c5-3eaba97c87a7" xlink:to="loc_us-gaap_GuaranteeObligationsNatureDomain_d7b8a5b0-2d0b-4dfe-a2f6-b78a3b74ebf8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_StandbyLettersOfCreditBondsAndBankGuaranteesMember_7aff1a35-2940-40c1-b50e-10ee2c5ce712" xlink:href="hsc-20211231.xsd#hsc_StandbyLettersOfCreditBondsAndBankGuaranteesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsNatureDomain_d7b8a5b0-2d0b-4dfe-a2f6-b78a3b74ebf8" xlink:to="loc_hsc_StandbyLettersOfCreditBondsAndBankGuaranteesMember_7aff1a35-2940-40c1-b50e-10ee2c5ce712" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndemnificationGuaranteeMember_7b5a6d0a-a8f4-4ca7-850a-93e956bc7542" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IndemnificationGuaranteeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsNatureDomain_d7b8a5b0-2d0b-4dfe-a2f6-b78a3b74ebf8" xlink:to="loc_us-gaap_IndemnificationGuaranteeMember_7b5a6d0a-a8f4-4ca7-850a-93e956bc7542" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_c47af8aa-8c5e-401a-9faa-ce4c79090284" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGuaranteeObligationsTable_9a396af2-1f36-471f-bd58-019e3d69c0d7" xlink:to="loc_srt_RangeAxis_c47af8aa-8c5e-401a-9faa-ce4c79090284" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_c47af8aa-8c5e-401a-9faa-ce4c79090284_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_c47af8aa-8c5e-401a-9faa-ce4c79090284" xlink:to="loc_srt_RangeMember_c47af8aa-8c5e-401a-9faa-ce4c79090284_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_a8c5003f-d1fe-41a2-9459-279a8182df87" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_c47af8aa-8c5e-401a-9faa-ce4c79090284" xlink:to="loc_srt_RangeMember_a8c5003f-d1fe-41a2-9459-279a8182df87" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_a6f9d35e-b41f-4386-990c-dd90e9c736ea" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_a8c5003f-d1fe-41a2-9459-279a8182df87" xlink:to="loc_srt_MinimumMember_a6f9d35e-b41f-4386-990c-dd90e9c736ea" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_67783726-0129-407a-8094-67a9c3abb0d3" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_a8c5003f-d1fe-41a2-9459-279a8182df87" xlink:to="loc_srt_MaximumMember_67783726-0129-407a-8094-67a9c3abb0d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_d4d07de3-acf3-4ca4-8324-66b417e6f09a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGuaranteeObligationsTable_9a396af2-1f36-471f-bd58-019e3d69c0d7" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_d4d07de3-acf3-4ca4-8324-66b417e6f09a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_d4d07de3-acf3-4ca4-8324-66b417e6f09a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_d4d07de3-acf3-4ca4-8324-66b417e6f09a" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_d4d07de3-acf3-4ca4-8324-66b417e6f09a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_edd4b8bb-af75-452f-a848-e8b2d693397a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_d4d07de3-acf3-4ca4-8324-66b417e6f09a" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_edd4b8bb-af75-452f-a848-e8b2d693397a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeForwardMember_5ccd58d2-09c3-44ef-ac29-4de99ba984a7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ForeignExchangeForwardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_edd4b8bb-af75-452f-a848-e8b2d693397a" xlink:to="loc_us-gaap_ForeignExchangeForwardMember_5ccd58d2-09c3-44ef-ac29-4de99ba984a7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_f96b3c0c-7f46-4d0e-a228-fba2fe0edce6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_edd4b8bb-af75-452f-a848-e8b2d693397a" xlink:to="loc_us-gaap_InterestRateSwapMember_f96b3c0c-7f46-4d0e-a228-fba2fe0edce6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_f54a3f02-0800-476c-9205-9b9c3c38d3b4" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGuaranteeObligationsTable_9a396af2-1f36-471f-bd58-019e3d69c0d7" xlink:to="loc_srt_StatementScenarioAxis_f54a3f02-0800-476c-9205-9b9c3c38d3b4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_f54a3f02-0800-476c-9205-9b9c3c38d3b4_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_f54a3f02-0800-476c-9205-9b9c3c38d3b4" xlink:to="loc_srt_ScenarioUnspecifiedDomain_f54a3f02-0800-476c-9205-9b9c3c38d3b4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_69fb527d-b665-42f5-88ee-d4281c3e1d9d" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_f54a3f02-0800-476c-9205-9b9c3c38d3b4" xlink:to="loc_srt_ScenarioUnspecifiedDomain_69fb527d-b665-42f5-88ee-d4281c3e1d9d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioForecastMember_73ebf27e-13fb-46d6-ae3c-f8356746e105" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ScenarioForecastMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ScenarioUnspecifiedDomain_69fb527d-b665-42f5-88ee-d4281c3e1d9d" xlink:to="loc_srt_ScenarioForecastMember_73ebf27e-13fb-46d6-ae3c-f8356746e105" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_21fc5b44-0279-4e65-91ef-dabe43f4e634" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGuaranteeObligationsTable_9a396af2-1f36-471f-bd58-019e3d69c0d7" xlink:to="loc_us-gaap_VariableRateAxis_21fc5b44-0279-4e65-91ef-dabe43f4e634" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_21fc5b44-0279-4e65-91ef-dabe43f4e634_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_21fc5b44-0279-4e65-91ef-dabe43f4e634" xlink:to="loc_us-gaap_VariableRateDomain_21fc5b44-0279-4e65-91ef-dabe43f4e634_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_b242ef11-2ff3-4de3-ae0d-f471e39863bf" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_21fc5b44-0279-4e65-91ef-dabe43f4e634" xlink:to="loc_us-gaap_VariableRateDomain_b242ef11-2ff3-4de3-ae0d-f471e39863bf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_48a1e71e-ca9b-4a99-bfbc-2a5d7f395bf6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_b242ef11-2ff3-4de3-ae0d-f471e39863bf" xlink:to="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_48a1e71e-ca9b-4a99-bfbc-2a5d7f395bf6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_376a5d8c-5e45-428d-a1f0-2aecc448a114" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGuaranteeObligationsTable_9a396af2-1f36-471f-bd58-019e3d69c0d7" xlink:to="loc_us-gaap_DebtInstrumentAxis_376a5d8c-5e45-428d-a1f0-2aecc448a114" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_376a5d8c-5e45-428d-a1f0-2aecc448a114_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_376a5d8c-5e45-428d-a1f0-2aecc448a114" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_376a5d8c-5e45-428d-a1f0-2aecc448a114_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_1903fc0a-f67d-4919-a532-b0b58ac70ce4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_376a5d8c-5e45-428d-a1f0-2aecc448a114" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_1903fc0a-f67d-4919-a532-b0b58ac70ce4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_TermLoanFacilityFixedRateMember_9060a984-92fd-4c4b-acb0-7b5264c32367" xlink:href="hsc-20211231.xsd#hsc_TermLoanFacilityFixedRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_1903fc0a-f67d-4919-a532-b0b58ac70ce4" xlink:to="loc_hsc_TermLoanFacilityFixedRateMember_9060a984-92fd-4c4b-acb0-7b5264c32367" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_8e1c1bf4-adc2-4c86-852f-67ec4d6c2ba0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGuaranteeObligationsTable_9a396af2-1f36-471f-bd58-019e3d69c0d7" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_8e1c1bf4-adc2-4c86-852f-67ec4d6c2ba0" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_8e1c1bf4-adc2-4c86-852f-67ec4d6c2ba0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_8e1c1bf4-adc2-4c86-852f-67ec4d6c2ba0" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_8e1c1bf4-adc2-4c86-852f-67ec4d6c2ba0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_903dc1d2-01ae-46d7-bc67-76f9f87b8907" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_8e1c1bf4-adc2-4c86-852f-67ec4d6c2ba0" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_903dc1d2-01ae-46d7-bc67-76f9f87b8907" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_TermLoanMember_d7aa9dc0-26d0-486a-9aa1-1ec555472462" xlink:href="hsc-20211231.xsd#hsc_TermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_903dc1d2-01ae-46d7-bc67-76f9f87b8907" xlink:to="loc_hsc_TermLoanMember_d7aa9dc0-26d0-486a-9aa1-1ec555472462" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/FinancialInstrumentsFairValueofOutstandingDerivativeContractsRecordedasAssetsandLiabilitiesDetails" xlink:type="simple" xlink:href="hsc-20211231.xsd#FinancialInstrumentsFairValueofOutstandingDerivativeContractsRecordedasAssetsandLiabilitiesDetails"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/FinancialInstrumentsFairValueofOutstandingDerivativeContractsRecordedasAssetsandLiabilitiesDetails" xlink:type="extended" id="i120115de85244f93bf65569b67bd039f_FinancialInstrumentsFairValueofOutstandingDerivativeContractsRecordedasAssetsandLiabilitiesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativesFairValueLineItems_faa14642-962c-4e58-bef8-985ade3e7206" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativesFairValueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_e5658553-83da-4bad-9034-f5c703faf176" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_faa14642-962c-4e58-bef8-985ade3e7206" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_e5658553-83da-4bad-9034-f5c703faf176" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_7c1a05e3-a5eb-4e32-9153-35d10dbf6709" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_faa14642-962c-4e58-bef8-985ade3e7206" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_7c1a05e3-a5eb-4e32-9153-35d10dbf6709" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_8ee10473-1864-4d81-a1f9-ee6bbeb65252" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_faa14642-962c-4e58-bef8-985ade3e7206" xlink:to="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_8ee10473-1864-4d81-a1f9-ee6bbeb65252" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_6779931b-44f1-4633-9aa3-c7e9129ad632" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_8ee10473-1864-4d81-a1f9-ee6bbeb65252" xlink:to="loc_us-gaap_HedgingDesignationAxis_6779931b-44f1-4633-9aa3-c7e9129ad632" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_6779931b-44f1-4633-9aa3-c7e9129ad632_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_6779931b-44f1-4633-9aa3-c7e9129ad632" xlink:to="loc_us-gaap_HedgingDesignationDomain_6779931b-44f1-4633-9aa3-c7e9129ad632_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_4d104f6e-fca7-492a-bf8a-2a1190602e6a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_6779931b-44f1-4633-9aa3-c7e9129ad632" xlink:to="loc_us-gaap_HedgingDesignationDomain_4d104f6e-fca7-492a-bf8a-2a1190602e6a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_446d4777-549e-4efc-87c6-72fea09fcdad" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_4d104f6e-fca7-492a-bf8a-2a1190602e6a" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_446d4777-549e-4efc-87c6-72fea09fcdad" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_061eefc4-e189-4a75-a8c2-b19564f71705" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NondesignatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_4d104f6e-fca7-492a-bf8a-2a1190602e6a" xlink:to="loc_us-gaap_NondesignatedMember_061eefc4-e189-4a75-a8c2-b19564f71705" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_000390a3-4107-41e6-a284-fd21e3031736" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_8ee10473-1864-4d81-a1f9-ee6bbeb65252" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_000390a3-4107-41e6-a284-fd21e3031736" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_000390a3-4107-41e6-a284-fd21e3031736_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_000390a3-4107-41e6-a284-fd21e3031736" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_000390a3-4107-41e6-a284-fd21e3031736_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_3febae08-a46b-4744-9e75-b977f91c5c98" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_000390a3-4107-41e6-a284-fd21e3031736" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_3febae08-a46b-4744-9e75-b977f91c5c98" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeForwardMember_07dcee42-77ad-47aa-862b-237002bd893e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ForeignExchangeForwardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_3febae08-a46b-4744-9e75-b977f91c5c98" xlink:to="loc_us-gaap_ForeignExchangeForwardMember_07dcee42-77ad-47aa-862b-237002bd893e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_1b4165ca-f932-41e6-aeb5-ac7bd3766aba" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_3febae08-a46b-4744-9e75-b977f91c5c98" xlink:to="loc_us-gaap_InterestRateSwapMember_1b4165ca-f932-41e6-aeb5-ac7bd3766aba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_7abe2daa-fda8-4692-bf67-b2acd70b2811" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_8ee10473-1864-4d81-a1f9-ee6bbeb65252" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_7abe2daa-fda8-4692-bf67-b2acd70b2811" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_7abe2daa-fda8-4692-bf67-b2acd70b2811_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_7abe2daa-fda8-4692-bf67-b2acd70b2811" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_7abe2daa-fda8-4692-bf67-b2acd70b2811_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_148a30b0-6225-4d3a-97d2-81d778ad179f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_7abe2daa-fda8-4692-bf67-b2acd70b2811" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_148a30b0-6225-4d3a-97d2-81d778ad179f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCurrentAssetsMember_3ad82156-60bc-4356-9732-806a36728c7b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherCurrentAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_148a30b0-6225-4d3a-97d2-81d778ad179f" xlink:to="loc_us-gaap_OtherCurrentAssetsMember_3ad82156-60bc-4356-9732-806a36728c7b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCurrentLiabilitiesMember_7fdf4fd7-50ef-4390-92f5-68d78f7ad5a7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherCurrentLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_148a30b0-6225-4d3a-97d2-81d778ad179f" xlink:to="loc_us-gaap_OtherCurrentLiabilitiesMember_7fdf4fd7-50ef-4390-92f5-68d78f7ad5a7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNoncurrentLiabilitiesMember_4ab91ee8-66a8-423c-b9ae-51e90f32098a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherNoncurrentLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_148a30b0-6225-4d3a-97d2-81d778ad179f" xlink:to="loc_us-gaap_OtherNoncurrentLiabilitiesMember_4ab91ee8-66a8-423c-b9ae-51e90f32098a" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/FinancialInstrumentsEffectofDerivativeInstrumentsontheConsolidatedStatementsofOperationsandtheConsolidatedStatementsofComprehensiveIncomeLossDetails" xlink:type="simple" xlink:href="hsc-20211231.xsd#FinancialInstrumentsEffectofDerivativeInstrumentsontheConsolidatedStatementsofOperationsandtheConsolidatedStatementsofComprehensiveIncomeLossDetails"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/FinancialInstrumentsEffectofDerivativeInstrumentsontheConsolidatedStatementsofOperationsandtheConsolidatedStatementsofComprehensiveIncomeLossDetails" xlink:type="extended" id="i047bcb9e20db4e91ae30302288ec478a_FinancialInstrumentsEffectofDerivativeInstrumentsontheConsolidatedStatementsofOperationsandtheConsolidatedStatementsofComprehensiveIncomeLossDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_76b6045c-10c4-405f-9037-11e24c74c9e0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_e443a87f-7553-4e90-b9cd-2abaf733db4b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_76b6045c-10c4-405f-9037-11e24c74c9e0" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_e443a87f-7553-4e90-b9cd-2abaf733db4b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_e72aeb29-18e9-452a-b8b6-837f142222e3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CostOfGoodsAndServicesSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_76b6045c-10c4-405f-9037-11e24c74c9e0" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_e72aeb29-18e9-452a-b8b6-837f142222e3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_3e9cda60-989e-4503-bb4d-3231ef8a515a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_76b6045c-10c4-405f-9037-11e24c74c9e0" xlink:to="loc_us-gaap_InterestExpense_3e9cda60-989e-4503-bb4d-3231ef8a515a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax_73d4307a-72e4-4170-9e29-5df30b3bb3c5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_76b6045c-10c4-405f-9037-11e24c74c9e0" xlink:to="loc_us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax_73d4307a-72e4-4170-9e29-5df30b3bb3c5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax_97229622-6879-407a-afb1-2dd17340019c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_76b6045c-10c4-405f-9037-11e24c74c9e0" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax_97229622-6879-407a-afb1-2dd17340019c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseBasedOnAmortizationApproachBeforeAdjustmentsAndTax_ff9a292b-6352-4f43-97c7-d627e8c12bde" xlink:href="hsc-20211231.xsd#hsc_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseBasedOnAmortizationApproachBeforeAdjustmentsAndTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_76b6045c-10c4-405f-9037-11e24c74c9e0" xlink:to="loc_hsc_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseBasedOnAmortizationApproachBeforeAdjustmentsAndTax_ff9a292b-6352-4f43-97c7-d627e8c12bde" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnDiscontinuationOfCashFlowHedgeDueToForecastedTransactionProbableOfNotOccurringNet_2350a384-cba3-4229-ab27-5eec7661f8a7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GainLossOnDiscontinuationOfCashFlowHedgeDueToForecastedTransactionProbableOfNotOccurringNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_76b6045c-10c4-405f-9037-11e24c74c9e0" xlink:to="loc_us-gaap_GainLossOnDiscontinuationOfCashFlowHedgeDueToForecastedTransactionProbableOfNotOccurringNet_2350a384-cba3-4229-ab27-5eec7661f8a7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseBeforeAdjustmentsAndTax_4c52f131-9d1e-4fbd-8486-9e83ec1f5921" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseBeforeAdjustmentsAndTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_76b6045c-10c4-405f-9037-11e24c74c9e0" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseBeforeAdjustmentsAndTax_4c52f131-9d1e-4fbd-8486-9e83ec1f5921" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossRecognizedInIncomeIneffectivePortionAndAmountExcludedFromEffectivenessTestingNet_04650c0a-8665-40e7-bcf1-13737cc09279" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossRecognizedInIncomeIneffectivePortionAndAmountExcludedFromEffectivenessTestingNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_76b6045c-10c4-405f-9037-11e24c74c9e0" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossRecognizedInIncomeIneffectivePortionAndAmountExcludedFromEffectivenessTestingNet_04650c0a-8665-40e7-bcf1-13737cc09279" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNetAbstract_502adc6f-15d5-428c-8d90-692f1cf8d894" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_76b6045c-10c4-405f-9037-11e24c74c9e0" xlink:to="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNetAbstract_502adc6f-15d5-428c-8d90-692f1cf8d894" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet_9b5eb609-8479-46a2-af5a-71c1e236cfcc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNetAbstract_502adc6f-15d5-428c-8d90-692f1cf8d894" xlink:to="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet_9b5eb609-8479-46a2-af5a-71c1e236cfcc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_47903d6b-981d-4f2c-9143-175e41f2a8f4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_76b6045c-10c4-405f-9037-11e24c74c9e0" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_47903d6b-981d-4f2c-9143-175e41f2a8f4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_855f2dce-4b1d-4988-9d9c-d95b26f81623" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_47903d6b-981d-4f2c-9143-175e41f2a8f4" xlink:to="loc_srt_ProductOrServiceAxis_855f2dce-4b1d-4988-9d9c-d95b26f81623" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_855f2dce-4b1d-4988-9d9c-d95b26f81623_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_855f2dce-4b1d-4988-9d9c-d95b26f81623" xlink:to="loc_srt_ProductsAndServicesDomain_855f2dce-4b1d-4988-9d9c-d95b26f81623_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_c28aaa22-b27b-47ea-9d7e-81d47c914892" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_855f2dce-4b1d-4988-9d9c-d95b26f81623" xlink:to="loc_srt_ProductsAndServicesDomain_c28aaa22-b27b-47ea-9d7e-81d47c914892" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductMember_d6fab364-9f99-49ac-a727-519c529b0950" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProductMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_c28aaa22-b27b-47ea-9d7e-81d47c914892" xlink:to="loc_us-gaap_ProductMember_d6fab364-9f99-49ac-a727-519c529b0950" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServiceMember_9e96461d-2e7b-4863-9be4-5e1e86a57404" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ServiceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_c28aaa22-b27b-47ea-9d7e-81d47c914892" xlink:to="loc_us-gaap_ServiceMember_9e96461d-2e7b-4863-9be4-5e1e86a57404" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_9243c168-b3a7-44bd-bf9b-ed8be855e6c5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_47903d6b-981d-4f2c-9143-175e41f2a8f4" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_9243c168-b3a7-44bd-bf9b-ed8be855e6c5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_9243c168-b3a7-44bd-bf9b-ed8be855e6c5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_9243c168-b3a7-44bd-bf9b-ed8be855e6c5" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_9243c168-b3a7-44bd-bf9b-ed8be855e6c5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_b38a84a8-bf41-4f4e-80b2-71b828ff41e0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_9243c168-b3a7-44bd-bf9b-ed8be855e6c5" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_b38a84a8-bf41-4f4e-80b2-71b828ff41e0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeForwardMember_768f9a89-5ad3-4690-8518-b55c88eddaa5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ForeignExchangeForwardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_b38a84a8-bf41-4f4e-80b2-71b828ff41e0" xlink:to="loc_us-gaap_ForeignExchangeForwardMember_768f9a89-5ad3-4690-8518-b55c88eddaa5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ForeignExchangeForwardTwoMember_1f2d3a94-85c3-4a2d-b7c2-2fa653b7526b" xlink:href="hsc-20211231.xsd#hsc_ForeignExchangeForwardTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_b38a84a8-bf41-4f4e-80b2-71b828ff41e0" xlink:to="loc_hsc_ForeignExchangeForwardTwoMember_1f2d3a94-85c3-4a2d-b7c2-2fa653b7526b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_59c510b9-ed67-4e64-abfe-7c961dcf090d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_b38a84a8-bf41-4f4e-80b2-71b828ff41e0" xlink:to="loc_us-gaap_InterestRateSwapMember_59c510b9-ed67-4e64-abfe-7c961dcf090d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_InterestRateSwapTwoMember_b19f4b32-eeb3-4ce8-a6fb-ffa2e9979f8b" xlink:href="hsc-20211231.xsd#hsc_InterestRateSwapTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_b38a84a8-bf41-4f4e-80b2-71b828ff41e0" xlink:to="loc_hsc_InterestRateSwapTwoMember_b19f4b32-eeb3-4ce8-a6fb-ffa2e9979f8b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CrossCurrencyInterestRateContractMember_fcc0e9ce-cca7-4cbe-8511-bc3087e4dee8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CrossCurrencyInterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_b38a84a8-bf41-4f4e-80b2-71b828ff41e0" xlink:to="loc_us-gaap_CrossCurrencyInterestRateContractMember_fcc0e9ce-cca7-4cbe-8511-bc3087e4dee8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeContractMember_3538d360-75ea-4d09-b109-6ccefe1e7898" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ForeignExchangeContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_b38a84a8-bf41-4f4e-80b2-71b828ff41e0" xlink:to="loc_us-gaap_ForeignExchangeContractMember_3538d360-75ea-4d09-b109-6ccefe1e7898" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_088f7442-0606-4bd1-b6b4-0d5b4727686d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_47903d6b-981d-4f2c-9143-175e41f2a8f4" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_088f7442-0606-4bd1-b6b4-0d5b4727686d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_088f7442-0606-4bd1-b6b4-0d5b4727686d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_088f7442-0606-4bd1-b6b4-0d5b4727686d" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_088f7442-0606-4bd1-b6b4-0d5b4727686d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_ee9ea135-20dc-476e-8487-4456623b5aa1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_088f7442-0606-4bd1-b6b4-0d5b4727686d" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_ee9ea135-20dc-476e-8487-4456623b5aa1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfSalesMember_c82f7e28-3fe7-41c7-8ed0-95e03d0521d7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CostOfSalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_ee9ea135-20dc-476e-8487-4456623b5aa1" xlink:to="loc_us-gaap_CostOfSalesMember_c82f7e28-3fe7-41c7-8ed0-95e03d0521d7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_3d2df2ea-e0b7-42b0-aae4-5d4d79d5c73f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_ee9ea135-20dc-476e-8487-4456623b5aa1" xlink:to="loc_us-gaap_RetainedEarningsMember_3d2df2ea-e0b7-42b0-aae4-5d4d79d5c73f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseMember_91bd4005-dc5d-4525-8a2f-4b904dbcf83f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InterestExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_ee9ea135-20dc-476e-8487-4456623b5aa1" xlink:to="loc_us-gaap_InterestExpenseMember_91bd4005-dc5d-4525-8a2f-4b904dbcf83f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsTotalMember_84a38627-fd04-4df4-9c5a-88292773ceac" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CostOfGoodsTotalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_ee9ea135-20dc-476e-8487-4456623b5aa1" xlink:to="loc_us-gaap_CostOfGoodsTotalMember_84a38627-fd04-4df4-9c5a-88292773ceac" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationMember_cf698e64-7820-4079-aa14-451abe16996c" xlink:href="hsc-20211231.xsd#hsc_DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_ee9ea135-20dc-476e-8487-4456623b5aa1" xlink:to="loc_hsc_DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationMember_cf698e64-7820-4079-aa14-451abe16996c" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/FinancialInstrumentsEffectofDerivativesDetails" xlink:type="simple" xlink:href="hsc-20211231.xsd#FinancialInstrumentsEffectofDerivativesDetails"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/FinancialInstrumentsEffectofDerivativesDetails" xlink:type="extended" id="i531e7f9332aa47b2bf271f4680cdd75f_FinancialInstrumentsEffectofDerivativesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativesFairValueLineItems_a9e142db-5518-4f3d-966a-7e38664bf5fc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativesFairValueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax_02cdcad1-425a-43f8-ba67-d9504ee71605" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_a9e142db-5518-4f3d-966a-7e38664bf5fc" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax_02cdcad1-425a-43f8-ba67-d9504ee71605" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax_69b583e1-6073-4ffa-a9d6-31373f5aeba2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_a9e142db-5518-4f3d-966a-7e38664bf5fc" xlink:to="loc_us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax_69b583e1-6073-4ffa-a9d6-31373f5aeba2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax_ec8317d9-79f0-4a75-9eec-82c288cd754b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_a9e142db-5518-4f3d-966a-7e38664bf5fc" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax_ec8317d9-79f0-4a75-9eec-82c288cd754b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_3a155f42-9747-41a9-bd4c-73789d9c8965" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_a9e142db-5518-4f3d-966a-7e38664bf5fc" xlink:to="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_3a155f42-9747-41a9-bd4c-73789d9c8965" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_068fca9d-4336-482c-8cd4-6a83d4bd25a2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_3a155f42-9747-41a9-bd4c-73789d9c8965" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_068fca9d-4336-482c-8cd4-6a83d4bd25a2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_068fca9d-4336-482c-8cd4-6a83d4bd25a2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_068fca9d-4336-482c-8cd4-6a83d4bd25a2" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_068fca9d-4336-482c-8cd4-6a83d4bd25a2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_a9a4eceb-27c7-4105-861c-7a5d9f17319d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_068fca9d-4336-482c-8cd4-6a83d4bd25a2" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_a9a4eceb-27c7-4105-861c-7a5d9f17319d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfSalesMember_181e61ab-487f-45d6-be58-d0f11b6cfe88" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CostOfSalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_a9a4eceb-27c7-4105-861c-7a5d9f17319d" xlink:to="loc_us-gaap_CostOfSalesMember_181e61ab-487f-45d6-be58-d0f11b6cfe88" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_6e28f30e-8fc2-417c-83f2-3cba1139ea23" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_a9a4eceb-27c7-4105-861c-7a5d9f17319d" xlink:to="loc_us-gaap_RetainedEarningsMember_6e28f30e-8fc2-417c-83f2-3cba1139ea23" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationMember_14adc71d-e5ad-4ce9-84e1-a0600bd8dc0a" xlink:href="hsc-20211231.xsd#hsc_DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_a9a4eceb-27c7-4105-861c-7a5d9f17319d" xlink:to="loc_hsc_DiscontinuedOperationGainLossFromDisposalOfDiscontinuedOperationMember_14adc71d-e5ad-4ce9-84e1-a0600bd8dc0a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseMember_64d20981-ca68-4ef0-9bda-d2c3b969f921" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InterestExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_a9a4eceb-27c7-4105-861c-7a5d9f17319d" xlink:to="loc_us-gaap_InterestExpenseMember_64d20981-ca68-4ef0-9bda-d2c3b969f921" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationsHeldForSaleOrDisposedOfBySaleMember_19075ff9-71db-4591-bf48-a1f9b47ed5e2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DiscontinuedOperationsHeldForSaleOrDisposedOfBySaleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_a9a4eceb-27c7-4105-861c-7a5d9f17319d" xlink:to="loc_us-gaap_DiscontinuedOperationsHeldForSaleOrDisposedOfBySaleMember_19075ff9-71db-4591-bf48-a1f9b47ed5e2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_688dac1e-ec4e-447d-b8f8-51e1053620ce" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_3a155f42-9747-41a9-bd4c-73789d9c8965" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_688dac1e-ec4e-447d-b8f8-51e1053620ce" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_688dac1e-ec4e-447d-b8f8-51e1053620ce_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_688dac1e-ec4e-447d-b8f8-51e1053620ce" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_688dac1e-ec4e-447d-b8f8-51e1053620ce_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_b9bf4f4c-cd6e-4178-8ffc-940e5ce6ae53" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_688dac1e-ec4e-447d-b8f8-51e1053620ce" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_b9bf4f4c-cd6e-4178-8ffc-940e5ce6ae53" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeForwardMember_fe904693-d100-4b27-9441-0d099cdab2b3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ForeignExchangeForwardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_b9bf4f4c-cd6e-4178-8ffc-940e5ce6ae53" xlink:to="loc_us-gaap_ForeignExchangeForwardMember_fe904693-d100-4b27-9441-0d099cdab2b3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ForeignExchangeForwardTwoMember_5dbc2c02-332c-421d-a993-49094b33e54c" xlink:href="hsc-20211231.xsd#hsc_ForeignExchangeForwardTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_b9bf4f4c-cd6e-4178-8ffc-940e5ce6ae53" xlink:to="loc_hsc_ForeignExchangeForwardTwoMember_5dbc2c02-332c-421d-a993-49094b33e54c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_c560a20d-f2df-4379-b72f-6dce4d829dec" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_b9bf4f4c-cd6e-4178-8ffc-940e5ce6ae53" xlink:to="loc_us-gaap_InterestRateSwapMember_c560a20d-f2df-4379-b72f-6dce4d829dec" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_InterestRateSwapTwoMember_105650db-b7e4-49bf-bc06-8a15c4dd4181" xlink:href="hsc-20211231.xsd#hsc_InterestRateSwapTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_b9bf4f4c-cd6e-4178-8ffc-940e5ce6ae53" xlink:to="loc_hsc_InterestRateSwapTwoMember_105650db-b7e4-49bf-bc06-8a15c4dd4181" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CrossCurrencyInterestRateContractMember_6a5c5681-b3cd-4ebc-9f99-224cd71327d5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CrossCurrencyInterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_b9bf4f4c-cd6e-4178-8ffc-940e5ce6ae53" xlink:to="loc_us-gaap_CrossCurrencyInterestRateContractMember_6a5c5681-b3cd-4ebc-9f99-224cd71327d5" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/InformationbySegmentandGeographicAreaDetails" xlink:type="simple" xlink:href="hsc-20211231.xsd#InformationbySegmentandGeographicAreaDetails"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/InformationbySegmentandGeographicAreaDetails" xlink:type="extended" id="i29989ea94acf40bb9e70b82dbb1af642_InformationbySegmentandGeographicAreaDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EntityWideRevenueMajorCustomerLineItems_e1fc5f4e-e828-40da-9777-5c4f97dcb914" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EntityWideRevenueMajorCustomerLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_97a5ffbe-f8e8-4082-8787-9f7ad1368a38" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideRevenueMajorCustomerLineItems_e1fc5f4e-e828-40da-9777-5c4f97dcb914" xlink:to="loc_us-gaap_Revenues_97a5ffbe-f8e8-4082-8787-9f7ad1368a38" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments_06804736-cafc-4d5a-b6b3-809ce4fcd906" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NumberOfReportableSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideRevenueMajorCustomerLineItems_e1fc5f4e-e828-40da-9777-5c4f97dcb914" xlink:to="loc_us-gaap_NumberOfReportableSegments_06804736-cafc-4d5a-b6b3-809ce4fcd906" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_NumberOfMajorCustomers_b97064b3-3868-4547-860d-e36033983a21" xlink:href="hsc-20211231.xsd#hsc_NumberOfMajorCustomers"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideRevenueMajorCustomerLineItems_e1fc5f4e-e828-40da-9777-5c4f97dcb914" xlink:to="loc_hsc_NumberOfMajorCustomers_b97064b3-3868-4547-860d-e36033983a21" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_15654376-6036-4535-a0df-002de5693af1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EntityWideRevenueMajorCustomerLineItems_e1fc5f4e-e828-40da-9777-5c4f97dcb914" xlink:to="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_15654376-6036-4535-a0df-002de5693af1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_b4aef9a4-8bcf-4eca-9630-649e9e729991" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_15654376-6036-4535-a0df-002de5693af1" xlink:to="loc_srt_StatementGeographicalAxis_b4aef9a4-8bcf-4eca-9630-649e9e729991" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_b4aef9a4-8bcf-4eca-9630-649e9e729991_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_b4aef9a4-8bcf-4eca-9630-649e9e729991" xlink:to="loc_srt_SegmentGeographicalDomain_b4aef9a4-8bcf-4eca-9630-649e9e729991_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_22c7256a-0cbb-4b95-8d8e-ef671f15e30b" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_b4aef9a4-8bcf-4eca-9630-649e9e729991" xlink:to="loc_srt_SegmentGeographicalDomain_22c7256a-0cbb-4b95-8d8e-ef671f15e30b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_OtherCountriesMember_1f85abe6-f462-4307-a76b-605859a34831" xlink:href="hsc-20211231.xsd#hsc_OtherCountriesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_22c7256a-0cbb-4b95-8d8e-ef671f15e30b" xlink:to="loc_hsc_OtherCountriesMember_1f85abe6-f462-4307-a76b-605859a34831" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_509c04c8-5526-4ddf-b28b-d66be2a8b958" xlink:href="https://xbrl.sec.gov/country/2021/country-2021.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_22c7256a-0cbb-4b95-8d8e-ef671f15e30b" xlink:to="loc_country_US_509c04c8-5526-4ddf-b28b-d66be2a8b958" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_GB_2e987e1b-71c1-49fe-87ed-7f845b39dc57" xlink:href="https://xbrl.sec.gov/country/2021/country-2021.xsd#country_GB"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_22c7256a-0cbb-4b95-8d8e-ef671f15e30b" xlink:to="loc_country_GB_2e987e1b-71c1-49fe-87ed-7f845b39dc57" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_64f327dd-abf2-404d-87ce-37f579ecb2db" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_15654376-6036-4535-a0df-002de5693af1" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_64f327dd-abf2-404d-87ce-37f579ecb2db" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_64f327dd-abf2-404d-87ce-37f579ecb2db_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_64f327dd-abf2-404d-87ce-37f579ecb2db" xlink:to="loc_us-gaap_SegmentDomain_64f327dd-abf2-404d-87ce-37f579ecb2db_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_98347553-a098-4a33-9235-31be135358aa" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_64f327dd-abf2-404d-87ce-37f579ecb2db" xlink:to="loc_us-gaap_SegmentDomain_98347553-a098-4a33-9235-31be135358aa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoMetalsAndMineralsMember_10f41f11-4b60-4942-8190-36db87d0de66" xlink:href="hsc-20211231.xsd#hsc_HarscoMetalsAndMineralsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_98347553-a098-4a33-9235-31be135358aa" xlink:to="loc_hsc_HarscoMetalsAndMineralsMember_10f41f11-4b60-4942-8190-36db87d0de66" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoEnvironmentalSegmentMember_914869bf-8b73-4071-a940-3a6b533e741c" xlink:href="hsc-20211231.xsd#hsc_HarscoEnvironmentalSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_98347553-a098-4a33-9235-31be135358aa" xlink:to="loc_hsc_HarscoEnvironmentalSegmentMember_914869bf-8b73-4071-a940-3a6b533e741c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_CleanEarthMember_80dbb744-2767-4b1a-8199-711b2b919681" xlink:href="hsc-20211231.xsd#hsc_CleanEarthMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_98347553-a098-4a33-9235-31be135358aa" xlink:to="loc_hsc_CleanEarthMember_80dbb744-2767-4b1a-8199-711b2b919681" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoIndustrialMember_7d3fa207-53b3-46f5-912c-b66ce6164fbd" xlink:href="hsc-20211231.xsd#hsc_HarscoIndustrialMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_98347553-a098-4a33-9235-31be135358aa" xlink:to="loc_hsc_HarscoIndustrialMember_7d3fa207-53b3-46f5-912c-b66ce6164fbd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoRailMember_6e189b9d-d6d2-4cfa-8d91-a9894a553545" xlink:href="hsc-20211231.xsd#hsc_HarscoRailMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_98347553-a098-4a33-9235-31be135358aa" xlink:to="loc_hsc_HarscoRailMember_6e189b9d-d6d2-4cfa-8d91-a9894a553545" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/InformationbySegmentandGeographicAreaDetails2" xlink:type="simple" xlink:href="hsc-20211231.xsd#InformationbySegmentandGeographicAreaDetails2"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/InformationbySegmentandGeographicAreaDetails2" xlink:type="extended" id="ifaacfaf4283f4b4c9e7cb6d3a04fe06c_InformationbySegmentandGeographicAreaDetails2">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_5beb03ee-92ce-4739-99d5-31e228752116" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_d898d44d-e282-41d7-868f-5675e1b5227e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_5beb03ee-92ce-4739-99d5-31e228752116" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_d898d44d-e282-41d7-868f-5675e1b5227e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_e77e6e02-e297-450e-b3fd-81f0cbce9012" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_5beb03ee-92ce-4739-99d5-31e228752116" xlink:to="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_e77e6e02-e297-450e-b3fd-81f0cbce9012" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_caa12431-c0cb-409b-81d8-03fdb3f784fd" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_e77e6e02-e297-450e-b3fd-81f0cbce9012" xlink:to="loc_srt_StatementGeographicalAxis_caa12431-c0cb-409b-81d8-03fdb3f784fd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_caa12431-c0cb-409b-81d8-03fdb3f784fd_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_caa12431-c0cb-409b-81d8-03fdb3f784fd" xlink:to="loc_srt_SegmentGeographicalDomain_caa12431-c0cb-409b-81d8-03fdb3f784fd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_99ef91ca-77c2-408e-89dc-94e14ba9ba9d" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_caa12431-c0cb-409b-81d8-03fdb3f784fd" xlink:to="loc_srt_SegmentGeographicalDomain_99ef91ca-77c2-408e-89dc-94e14ba9ba9d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_6b630a90-034a-4266-a1d4-980289833d4a" xlink:href="https://xbrl.sec.gov/country/2021/country-2021.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_99ef91ca-77c2-408e-89dc-94e14ba9ba9d" xlink:to="loc_country_US_6b630a90-034a-4266-a1d4-980289833d4a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_GB_98699912-a759-44ae-ba34-58d02b372033" xlink:href="https://xbrl.sec.gov/country/2021/country-2021.xsd#country_GB"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_99ef91ca-77c2-408e-89dc-94e14ba9ba9d" xlink:to="loc_country_GB_98699912-a759-44ae-ba34-58d02b372033" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_CN_3860083b-e9b6-4bed-97fc-6b8084690c33" xlink:href="https://xbrl.sec.gov/country/2021/country-2021.xsd#country_CN"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_99ef91ca-77c2-408e-89dc-94e14ba9ba9d" xlink:to="loc_country_CN_3860083b-e9b6-4bed-97fc-6b8084690c33" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_OtherCountriesMember_5d92a42e-9772-4098-8d50-4ddc079f3912" xlink:href="hsc-20211231.xsd#hsc_OtherCountriesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_99ef91ca-77c2-408e-89dc-94e14ba9ba9d" xlink:to="loc_hsc_OtherCountriesMember_5d92a42e-9772-4098-8d50-4ddc079f3912" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/InformationbySegmentandGeographicAreaDetails3" xlink:type="simple" xlink:href="hsc-20211231.xsd#InformationbySegmentandGeographicAreaDetails3"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/InformationbySegmentandGeographicAreaDetails3" xlink:type="extended" id="i41be95c92a0a4dbaad296077cc35c3da_InformationbySegmentandGeographicAreaDetails3">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_b019c5a0-0f7d-4038-b352-162490cf9e8d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_ba64d9b9-9d5a-47d4-93ce-a711ffd8bc1e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_b019c5a0-0f7d-4038-b352-162490cf9e8d" xlink:to="loc_us-gaap_Revenues_ba64d9b9-9d5a-47d4-93ce-a711ffd8bc1e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_13d99aa7-fb1c-4342-950a-455b5dfb4e88" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_b019c5a0-0f7d-4038-b352-162490cf9e8d" xlink:to="loc_us-gaap_OperatingIncomeLoss_13d99aa7-fb1c-4342-950a-455b5dfb4e88" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_eacd4f71-9da8-492c-bf3a-1eab4cadfa06" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_b019c5a0-0f7d-4038-b352-162490cf9e8d" xlink:to="loc_us-gaap_Assets_eacd4f71-9da8-492c-bf3a-1eab4cadfa06" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_bca25793-71bf-45f1-951d-7c1026d894ed" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_Depreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_b019c5a0-0f7d-4038-b352-162490cf9e8d" xlink:to="loc_us-gaap_Depreciation_bca25793-71bf-45f1-951d-7c1026d894ed" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DepreciationExcludingIndustrialSegment_caf70c48-4231-4c65-ad29-baaac591b350" xlink:href="hsc-20211231.xsd#hsc_DepreciationExcludingIndustrialSegment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_b019c5a0-0f7d-4038-b352-162490cf9e8d" xlink:to="loc_hsc_DepreciationExcludingIndustrialSegment_caf70c48-4231-4c65-ad29-baaac591b350" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentForAmortization_92d9af2a-fe50-4f3c-bf79-dc0ab4eaf94d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AdjustmentForAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_b019c5a0-0f7d-4038-b352-162490cf9e8d" xlink:to="loc_us-gaap_AdjustmentForAmortization_92d9af2a-fe50-4f3c-bf79-dc0ab4eaf94d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_AmortizationExcludingDeferredFinancingCosts_ea24b09a-c213-4c3f-9d58-3de576081ae4" xlink:href="hsc-20211231.xsd#hsc_AmortizationExcludingDeferredFinancingCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_b019c5a0-0f7d-4038-b352-162490cf9e8d" xlink:to="loc_hsc_AmortizationExcludingDeferredFinancingCosts_ea24b09a-c213-4c3f-9d58-3de576081ae4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireProductiveAssets_aa1f3977-e335-4338-91ab-a704a9041aa1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsToAcquireProductiveAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_b019c5a0-0f7d-4038-b352-162490cf9e8d" xlink:to="loc_us-gaap_PaymentsToAcquireProductiveAssets_aa1f3977-e335-4338-91ab-a704a9041aa1" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentIncomeInterest_bf18d8b9-2988-4dd8-96a3-893ae74c2b7b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InvestmentIncomeInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_b019c5a0-0f7d-4038-b352-162490cf9e8d" xlink:to="loc_us-gaap_InvestmentIncomeInterest_bf18d8b9-2988-4dd8-96a3-893ae74c2b7b" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_ef28bdd3-ded4-4a14-addf-99ca7b304331" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_b019c5a0-0f7d-4038-b352-162490cf9e8d" xlink:to="loc_us-gaap_InterestExpense_ef28bdd3-ded4-4a14-addf-99ca7b304331" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionExpenseReversalOfExpenseNoncash_a677ff52-a499-41b8-b646-f567c0b39847" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PensionExpenseReversalOfExpenseNoncash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_b019c5a0-0f7d-4038-b352-162490cf9e8d" xlink:to="loc_us-gaap_PensionExpenseReversalOfExpenseNoncash_a677ff52-a499-41b8-b646-f567c0b39847" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingExpense_69c49daa-7be8-4d97-b4fe-f6997c264211" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherNonoperatingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_b019c5a0-0f7d-4038-b352-162490cf9e8d" xlink:to="loc_us-gaap_OtherNonoperatingExpense_69c49daa-7be8-4d97-b4fe-f6997c264211" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_dfe5db8b-d355-445c-804e-88f3484da5de" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_b019c5a0-0f7d-4038-b352-162490cf9e8d" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_dfe5db8b-d355-445c-804e-88f3484da5de" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_ab497689-5820-4134-a226-250804686afd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_b019c5a0-0f7d-4038-b352-162490cf9e8d" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_ab497689-5820-4134-a226-250804686afd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_670af509-21b7-4fa4-a265-0b72f41ed208" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_ab497689-5820-4134-a226-250804686afd" xlink:to="loc_srt_ConsolidationItemsAxis_670af509-21b7-4fa4-a265-0b72f41ed208" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_670af509-21b7-4fa4-a265-0b72f41ed208_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_670af509-21b7-4fa4-a265-0b72f41ed208" xlink:to="loc_srt_ConsolidationItemsDomain_670af509-21b7-4fa4-a265-0b72f41ed208_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_6d4fb099-c1e7-4294-9abb-76cbd31f0dee" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_670af509-21b7-4fa4-a265-0b72f41ed208" xlink:to="loc_srt_ConsolidationItemsDomain_6d4fb099-c1e7-4294-9abb-76cbd31f0dee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_dabdc413-aa54-4fb7-b6a7-e56112c81576" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_6d4fb099-c1e7-4294-9abb-76cbd31f0dee" xlink:to="loc_us-gaap_OperatingSegmentsMember_dabdc413-aa54-4fb7-b6a7-e56112c81576" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNonSegmentMember_f761b0a3-1e96-42ac-b40d-9086ffd11bea" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CorporateNonSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_6d4fb099-c1e7-4294-9abb-76cbd31f0dee" xlink:to="loc_us-gaap_CorporateNonSegmentMember_f761b0a3-1e96-42ac-b40d-9086ffd11bea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_356b06ed-ed90-4821-86a4-a42a9dabeb63" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_ab497689-5820-4134-a226-250804686afd" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_356b06ed-ed90-4821-86a4-a42a9dabeb63" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_356b06ed-ed90-4821-86a4-a42a9dabeb63_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_356b06ed-ed90-4821-86a4-a42a9dabeb63" xlink:to="loc_us-gaap_SegmentDomain_356b06ed-ed90-4821-86a4-a42a9dabeb63_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_a80e08e4-856f-4b1f-a2f2-7b29da69096f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_356b06ed-ed90-4821-86a4-a42a9dabeb63" xlink:to="loc_us-gaap_SegmentDomain_a80e08e4-856f-4b1f-a2f2-7b29da69096f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoEnvironmentalSegmentMember_acdf91a0-9c32-4894-a365-c204db8a0c38" xlink:href="hsc-20211231.xsd#hsc_HarscoEnvironmentalSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_a80e08e4-856f-4b1f-a2f2-7b29da69096f" xlink:to="loc_hsc_HarscoEnvironmentalSegmentMember_acdf91a0-9c32-4894-a365-c204db8a0c38" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_CleanEarthMember_b2190623-ff3a-4e1b-95f0-6f953abc6139" xlink:href="hsc-20211231.xsd#hsc_CleanEarthMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_a80e08e4-856f-4b1f-a2f2-7b29da69096f" xlink:to="loc_hsc_CleanEarthMember_b2190623-ff3a-4e1b-95f0-6f953abc6139" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoIndustrialMember_ce6f62c2-4e16-4dae-8ec7-01cef2a44340" xlink:href="hsc-20211231.xsd#hsc_HarscoIndustrialMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_a80e08e4-856f-4b1f-a2f2-7b29da69096f" xlink:to="loc_hsc_HarscoIndustrialMember_ce6f62c2-4e16-4dae-8ec7-01cef2a44340" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoRailMember_bb470dc0-ef30-43fa-be3c-3d9c3be5d463" xlink:href="hsc-20211231.xsd#hsc_HarscoRailMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_a80e08e4-856f-4b1f-a2f2-7b29da69096f" xlink:to="loc_hsc_HarscoRailMember_bb470dc0-ef30-43fa-be3c-3d9c3be5d463" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/RevenueRecognitionSummaryofRevenuesbyPrimaryGeographicalMarketsDetails" xlink:type="simple" xlink:href="hsc-20211231.xsd#RevenueRecognitionSummaryofRevenuesbyPrimaryGeographicalMarketsDetails"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/RevenueRecognitionSummaryofRevenuesbyPrimaryGeographicalMarketsDetails" xlink:type="extended" id="iaebaae5160f148ce9cde234515bec72c_RevenueRecognitionSummaryofRevenuesbyPrimaryGeographicalMarketsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_9d7ebb92-a625-432d-8bc8-c912118f2d27" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_2b144785-c7f8-4fd4-bb69-8afd70b7711a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_9d7ebb92-a625-432d-8bc8-c912118f2d27" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_2b144785-c7f8-4fd4-bb69-8afd70b7711a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_7fecf9af-ea87-4f30-ab1a-c46a189c7d97" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_9d7ebb92-a625-432d-8bc8-c912118f2d27" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_7fecf9af-ea87-4f30-ab1a-c46a189c7d97" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_61f6cbc8-4766-4fd9-860f-14a8e42c7f48" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_7fecf9af-ea87-4f30-ab1a-c46a189c7d97" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_61f6cbc8-4766-4fd9-860f-14a8e42c7f48" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_61f6cbc8-4766-4fd9-860f-14a8e42c7f48_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_61f6cbc8-4766-4fd9-860f-14a8e42c7f48" xlink:to="loc_us-gaap_SegmentDomain_61f6cbc8-4766-4fd9-860f-14a8e42c7f48_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_9f32d2dd-9971-42ca-9fbf-d1dba02e442e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_61f6cbc8-4766-4fd9-860f-14a8e42c7f48" xlink:to="loc_us-gaap_SegmentDomain_9f32d2dd-9971-42ca-9fbf-d1dba02e442e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoEnvironmentalSegmentMember_ac5b3a18-c34c-448a-b3fb-295f68041bb8" xlink:href="hsc-20211231.xsd#hsc_HarscoEnvironmentalSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_9f32d2dd-9971-42ca-9fbf-d1dba02e442e" xlink:to="loc_hsc_HarscoEnvironmentalSegmentMember_ac5b3a18-c34c-448a-b3fb-295f68041bb8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_CleanEarthMember_d29807cb-9771-459b-88a2-7793bae981d6" xlink:href="hsc-20211231.xsd#hsc_CleanEarthMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_9f32d2dd-9971-42ca-9fbf-d1dba02e442e" xlink:to="loc_hsc_CleanEarthMember_d29807cb-9771-459b-88a2-7793bae981d6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoRailMember_420eb3b7-0a3f-4888-a371-00eda449cd3f" xlink:href="hsc-20211231.xsd#hsc_HarscoRailMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_9f32d2dd-9971-42ca-9fbf-d1dba02e442e" xlink:to="loc_hsc_HarscoRailMember_420eb3b7-0a3f-4888-a371-00eda449cd3f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_08b32f42-e880-4ff5-9e98-4dd7ea48fe91" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_7fecf9af-ea87-4f30-ab1a-c46a189c7d97" xlink:to="loc_srt_ConsolidationItemsAxis_08b32f42-e880-4ff5-9e98-4dd7ea48fe91" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_08b32f42-e880-4ff5-9e98-4dd7ea48fe91_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_08b32f42-e880-4ff5-9e98-4dd7ea48fe91" xlink:to="loc_srt_ConsolidationItemsDomain_08b32f42-e880-4ff5-9e98-4dd7ea48fe91_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_525a8144-4d94-463b-920f-2453ef78d4ce" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_08b32f42-e880-4ff5-9e98-4dd7ea48fe91" xlink:to="loc_srt_ConsolidationItemsDomain_525a8144-4d94-463b-920f-2453ef78d4ce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_bce93164-8ee1-4119-9f90-1f3cad6e2d91" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_525a8144-4d94-463b-920f-2453ef78d4ce" xlink:to="loc_us-gaap_OperatingSegmentsMember_bce93164-8ee1-4119-9f90-1f3cad6e2d91" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNonSegmentMember_85d1e807-7909-45a5-bd59-648fd31c0b80" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CorporateNonSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_525a8144-4d94-463b-920f-2453ef78d4ce" xlink:to="loc_us-gaap_CorporateNonSegmentMember_85d1e807-7909-45a5-bd59-648fd31c0b80" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_1743a60b-10f8-469d-a7a0-d86ac71c134d" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_7fecf9af-ea87-4f30-ab1a-c46a189c7d97" xlink:to="loc_srt_StatementGeographicalAxis_1743a60b-10f8-469d-a7a0-d86ac71c134d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_1743a60b-10f8-469d-a7a0-d86ac71c134d_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_1743a60b-10f8-469d-a7a0-d86ac71c134d" xlink:to="loc_srt_SegmentGeographicalDomain_1743a60b-10f8-469d-a7a0-d86ac71c134d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_53ea1ed4-7a9e-4710-94a7-c4d152c96286" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_1743a60b-10f8-469d-a7a0-d86ac71c134d" xlink:to="loc_srt_SegmentGeographicalDomain_53ea1ed4-7a9e-4710-94a7-c4d152c96286" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NorthAmericaMember_6937a259-9323-426d-a1ee-3b74a057deca" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_NorthAmericaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_53ea1ed4-7a9e-4710-94a7-c4d152c96286" xlink:to="loc_srt_NorthAmericaMember_6937a259-9323-426d-a1ee-3b74a057deca" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_WesternEuropeMember_92aa1e41-6a69-441d-9653-04a5b1e667ab" xlink:href="hsc-20211231.xsd#hsc_WesternEuropeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_53ea1ed4-7a9e-4710-94a7-c4d152c96286" xlink:to="loc_hsc_WesternEuropeMember_92aa1e41-6a69-441d-9653-04a5b1e667ab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LatinAmericaMember_b26f6dc7-5433-4ba5-8739-2c464ceda05d" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_LatinAmericaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_53ea1ed4-7a9e-4710-94a7-c4d152c96286" xlink:to="loc_srt_LatinAmericaMember_b26f6dc7-5433-4ba5-8739-2c464ceda05d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AsiaPacificMember_4d99f3e6-d4a6-4de7-838d-a7bdf8cfa756" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_AsiaPacificMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_53ea1ed4-7a9e-4710-94a7-c4d152c96286" xlink:to="loc_srt_AsiaPacificMember_4d99f3e6-d4a6-4de7-838d-a7bdf8cfa756" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_MiddleEastAndAfricaMember_66f9c700-ce1a-4059-9708-8fa37b89a600" xlink:href="hsc-20211231.xsd#hsc_MiddleEastAndAfricaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_53ea1ed4-7a9e-4710-94a7-c4d152c96286" xlink:to="loc_hsc_MiddleEastAndAfricaMember_66f9c700-ce1a-4059-9708-8fa37b89a600" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_EasternEuropeMember_7fad1e97-05e0-4b65-8e25-fc0353a77965" xlink:href="hsc-20211231.xsd#hsc_EasternEuropeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_53ea1ed4-7a9e-4710-94a7-c4d152c96286" xlink:to="loc_hsc_EasternEuropeMember_7fad1e97-05e0-4b65-8e25-fc0353a77965" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_5c14f6a2-d046-4d00-8c46-1661190f1742" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_7fecf9af-ea87-4f30-ab1a-c46a189c7d97" xlink:to="loc_srt_ProductOrServiceAxis_5c14f6a2-d046-4d00-8c46-1661190f1742" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_5c14f6a2-d046-4d00-8c46-1661190f1742_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_5c14f6a2-d046-4d00-8c46-1661190f1742" xlink:to="loc_srt_ProductsAndServicesDomain_5c14f6a2-d046-4d00-8c46-1661190f1742_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_64d7df2b-a350-4ab2-b0d8-416de16997ba" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_5c14f6a2-d046-4d00-8c46-1661190f1742" xlink:to="loc_srt_ProductsAndServicesDomain_64d7df2b-a350-4ab2-b0d8-416de16997ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ProductsAndServicesOnsiteServicesAndMaterialLogisticsProductQualityImprovementAndResourceRecoveryMember_989b5dd4-6539-49ab-8288-2cbec2fe75ec" xlink:href="hsc-20211231.xsd#hsc_ProductsAndServicesOnsiteServicesAndMaterialLogisticsProductQualityImprovementAndResourceRecoveryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_64d7df2b-a350-4ab2-b0d8-416de16997ba" xlink:to="loc_hsc_ProductsAndServicesOnsiteServicesAndMaterialLogisticsProductQualityImprovementAndResourceRecoveryMember_989b5dd4-6539-49ab-8288-2cbec2fe75ec" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_AppliedProductsMember_45e1058d-85bd-4ccb-9788-a90246f5ae4d" xlink:href="hsc-20211231.xsd#hsc_AppliedProductsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_64d7df2b-a350-4ab2-b0d8-416de16997ba" xlink:to="loc_hsc_AppliedProductsMember_45e1058d-85bd-4ccb-9788-a90246f5ae4d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_AluminumDrossAndScrapProcessingSystemsMember_6ae731bb-a74d-4daa-b19b-2195cd8ff8b0" xlink:href="hsc-20211231.xsd#hsc_AluminumDrossAndScrapProcessingSystemsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_64d7df2b-a350-4ab2-b0d8-416de16997ba" xlink:to="loc_hsc_AluminumDrossAndScrapProcessingSystemsMember_6ae731bb-a74d-4daa-b19b-2195cd8ff8b0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_WasteProcessingAndReuseSolutionsMember_0e26ff35-fac6-4a18-9cd9-b000f5fd9ef9" xlink:href="hsc-20211231.xsd#hsc_WasteProcessingAndReuseSolutionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_64d7df2b-a350-4ab2-b0d8-416de16997ba" xlink:to="loc_hsc_WasteProcessingAndReuseSolutionsMember_0e26ff35-fac6-4a18-9cd9-b000f5fd9ef9" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/RevenueRecognitionNarrativeDetails" xlink:type="simple" xlink:href="hsc-20211231.xsd#RevenueRecognitionNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/RevenueRecognitionNarrativeDetails" xlink:type="extended" id="i7c470e8e91ff48b2a87873e6310f7374_RevenueRecognitionNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_dbfa4ee8-e2de-4d32-862b-d44d250676b3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_f6106fb7-19aa-401d-8313-2e1dd194471a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_dbfa4ee8-e2de-4d32-862b-d44d250676b3" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_f6106fb7-19aa-401d-8313-2e1dd194471a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_b0da9918-0d76-4491-a09e-47c3124f57df" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_dbfa4ee8-e2de-4d32-862b-d44d250676b3" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_b0da9918-0d76-4491-a09e-47c3124f57df" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_10b86bfb-8b10-4a66-906a-784d721d1f02" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_b0da9918-0d76-4491-a09e-47c3124f57df" xlink:to="loc_srt_ConsolidationItemsAxis_10b86bfb-8b10-4a66-906a-784d721d1f02" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_10b86bfb-8b10-4a66-906a-784d721d1f02_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_10b86bfb-8b10-4a66-906a-784d721d1f02" xlink:to="loc_srt_ConsolidationItemsDomain_10b86bfb-8b10-4a66-906a-784d721d1f02_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_640a243f-3eae-436a-9132-0927319f58e0" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_10b86bfb-8b10-4a66-906a-784d721d1f02" xlink:to="loc_srt_ConsolidationItemsDomain_640a243f-3eae-436a-9132-0927319f58e0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_696033d9-7d7a-4379-9cda-976e7258aa2e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_640a243f-3eae-436a-9132-0927319f58e0" xlink:to="loc_us-gaap_OperatingSegmentsMember_696033d9-7d7a-4379-9cda-976e7258aa2e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNonSegmentMember_77618c22-7ff9-4d5d-ab01-9deaa7f22b02" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CorporateNonSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_640a243f-3eae-436a-9132-0927319f58e0" xlink:to="loc_us-gaap_CorporateNonSegmentMember_77618c22-7ff9-4d5d-ab01-9deaa7f22b02" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_e7b48843-22f4-4c7d-99f2-ad39d59964d9" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_b0da9918-0d76-4491-a09e-47c3124f57df" xlink:to="loc_srt_ProductOrServiceAxis_e7b48843-22f4-4c7d-99f2-ad39d59964d9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_e7b48843-22f4-4c7d-99f2-ad39d59964d9_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_e7b48843-22f4-4c7d-99f2-ad39d59964d9" xlink:to="loc_srt_ProductsAndServicesDomain_e7b48843-22f4-4c7d-99f2-ad39d59964d9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_e18c1c1a-4036-4f6b-b1bf-c3079d718918" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_e7b48843-22f4-4c7d-99f2-ad39d59964d9" xlink:to="loc_srt_ProductsAndServicesDomain_e18c1c1a-4036-4f6b-b1bf-c3079d718918" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_WasteProcessingAndReuseSolutionsMember_d0198bb6-899c-43a9-bb5c-a383f51d0e44" xlink:href="hsc-20211231.xsd#hsc_WasteProcessingAndReuseSolutionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_e18c1c1a-4036-4f6b-b1bf-c3079d718918" xlink:to="loc_hsc_WasteProcessingAndReuseSolutionsMember_d0198bb6-899c-43a9-bb5c-a383f51d0e44" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_AluminumDrossAndScrapProcessingSystemsMember_2f39aaf3-ac82-4486-bf5b-7315544da3ca" xlink:href="hsc-20211231.xsd#hsc_AluminumDrossAndScrapProcessingSystemsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_e18c1c1a-4036-4f6b-b1bf-c3079d718918" xlink:to="loc_hsc_AluminumDrossAndScrapProcessingSystemsMember_2f39aaf3-ac82-4486-bf5b-7315544da3ca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ProductsAndServicesOnsiteServicesAndMaterialLogisticsProductQualityImprovementAndResourceRecoveryMember_67ee92cf-623f-4250-8dfb-2ca0f23e7092" xlink:href="hsc-20211231.xsd#hsc_ProductsAndServicesOnsiteServicesAndMaterialLogisticsProductQualityImprovementAndResourceRecoveryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_e18c1c1a-4036-4f6b-b1bf-c3079d718918" xlink:to="loc_hsc_ProductsAndServicesOnsiteServicesAndMaterialLogisticsProductQualityImprovementAndResourceRecoveryMember_67ee92cf-623f-4250-8dfb-2ca0f23e7092" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_AppliedProductsMember_0b2b210a-e9b6-4686-b220-99cbe8a69ee7" xlink:href="hsc-20211231.xsd#hsc_AppliedProductsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_e18c1c1a-4036-4f6b-b1bf-c3079d718918" xlink:to="loc_hsc_AppliedProductsMember_0b2b210a-e9b6-4686-b220-99cbe8a69ee7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_f36d1a83-07d4-4f60-9ac8-cc40a56fc865" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_b0da9918-0d76-4491-a09e-47c3124f57df" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_f36d1a83-07d4-4f60-9ac8-cc40a56fc865" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_f36d1a83-07d4-4f60-9ac8-cc40a56fc865_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_f36d1a83-07d4-4f60-9ac8-cc40a56fc865" xlink:to="loc_us-gaap_SegmentDomain_f36d1a83-07d4-4f60-9ac8-cc40a56fc865_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_d3ef32eb-077b-41fd-b51d-70cf8ecf9f97" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_f36d1a83-07d4-4f60-9ac8-cc40a56fc865" xlink:to="loc_us-gaap_SegmentDomain_d3ef32eb-077b-41fd-b51d-70cf8ecf9f97" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_CleanEarthMember_5067d547-d71a-418f-ba64-7ef3bf00d419" xlink:href="hsc-20211231.xsd#hsc_CleanEarthMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_d3ef32eb-077b-41fd-b51d-70cf8ecf9f97" xlink:to="loc_hsc_CleanEarthMember_5067d547-d71a-418f-ba64-7ef3bf00d419" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoEnvironmentalSegmentMember_50ec1997-edc2-4b1f-b507-4708bc7f752b" xlink:href="hsc-20211231.xsd#hsc_HarscoEnvironmentalSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_d3ef32eb-077b-41fd-b51d-70cf8ecf9f97" xlink:to="loc_hsc_HarscoEnvironmentalSegmentMember_50ec1997-edc2-4b1f-b507-4708bc7f752b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_1ff9cdd4-6a4e-4dd7-8fbd-a1f1246b7a64" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_b0da9918-0d76-4491-a09e-47c3124f57df" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_1ff9cdd4-6a4e-4dd7-8fbd-a1f1246b7a64" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/RevenueRecognitionNarrativeDetails_1" xlink:type="simple" xlink:href="hsc-20211231.xsd#RevenueRecognitionNarrativeDetails_1"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/RevenueRecognitionNarrativeDetails_1" xlink:type="extended" id="i59c6c1c59a4f4633a2f2e769b073c440_RevenueRecognitionNarrativeDetails_1">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_dbfa4ee8-e2de-4d32-862b-d44d250676b3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_f6106fb7-19aa-401d-8313-2e1dd194471a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_dbfa4ee8-e2de-4d32-862b-d44d250676b3" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_f6106fb7-19aa-401d-8313-2e1dd194471a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_b0da9918-0d76-4491-a09e-47c3124f57df" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_dbfa4ee8-e2de-4d32-862b-d44d250676b3" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_b0da9918-0d76-4491-a09e-47c3124f57df" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_10b86bfb-8b10-4a66-906a-784d721d1f02" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_b0da9918-0d76-4491-a09e-47c3124f57df" xlink:to="loc_srt_ConsolidationItemsAxis_10b86bfb-8b10-4a66-906a-784d721d1f02" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_10b86bfb-8b10-4a66-906a-784d721d1f02_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_10b86bfb-8b10-4a66-906a-784d721d1f02" xlink:to="loc_srt_ConsolidationItemsDomain_10b86bfb-8b10-4a66-906a-784d721d1f02_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_640a243f-3eae-436a-9132-0927319f58e0" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_10b86bfb-8b10-4a66-906a-784d721d1f02" xlink:to="loc_srt_ConsolidationItemsDomain_640a243f-3eae-436a-9132-0927319f58e0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_696033d9-7d7a-4379-9cda-976e7258aa2e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_640a243f-3eae-436a-9132-0927319f58e0" xlink:to="loc_us-gaap_OperatingSegmentsMember_696033d9-7d7a-4379-9cda-976e7258aa2e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNonSegmentMember_77618c22-7ff9-4d5d-ab01-9deaa7f22b02" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CorporateNonSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_640a243f-3eae-436a-9132-0927319f58e0" xlink:to="loc_us-gaap_CorporateNonSegmentMember_77618c22-7ff9-4d5d-ab01-9deaa7f22b02" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_e7b48843-22f4-4c7d-99f2-ad39d59964d9" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_b0da9918-0d76-4491-a09e-47c3124f57df" xlink:to="loc_srt_ProductOrServiceAxis_e7b48843-22f4-4c7d-99f2-ad39d59964d9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_e7b48843-22f4-4c7d-99f2-ad39d59964d9_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_e7b48843-22f4-4c7d-99f2-ad39d59964d9" xlink:to="loc_srt_ProductsAndServicesDomain_e7b48843-22f4-4c7d-99f2-ad39d59964d9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_e18c1c1a-4036-4f6b-b1bf-c3079d718918" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_e7b48843-22f4-4c7d-99f2-ad39d59964d9" xlink:to="loc_srt_ProductsAndServicesDomain_e18c1c1a-4036-4f6b-b1bf-c3079d718918" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_WasteProcessingAndReuseSolutionsMember_d0198bb6-899c-43a9-bb5c-a383f51d0e44" xlink:href="hsc-20211231.xsd#hsc_WasteProcessingAndReuseSolutionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_e18c1c1a-4036-4f6b-b1bf-c3079d718918" xlink:to="loc_hsc_WasteProcessingAndReuseSolutionsMember_d0198bb6-899c-43a9-bb5c-a383f51d0e44" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_AluminumDrossAndScrapProcessingSystemsMember_2f39aaf3-ac82-4486-bf5b-7315544da3ca" xlink:href="hsc-20211231.xsd#hsc_AluminumDrossAndScrapProcessingSystemsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_e18c1c1a-4036-4f6b-b1bf-c3079d718918" xlink:to="loc_hsc_AluminumDrossAndScrapProcessingSystemsMember_2f39aaf3-ac82-4486-bf5b-7315544da3ca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ProductsAndServicesOnsiteServicesAndMaterialLogisticsProductQualityImprovementAndResourceRecoveryMember_67ee92cf-623f-4250-8dfb-2ca0f23e7092" xlink:href="hsc-20211231.xsd#hsc_ProductsAndServicesOnsiteServicesAndMaterialLogisticsProductQualityImprovementAndResourceRecoveryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_e18c1c1a-4036-4f6b-b1bf-c3079d718918" xlink:to="loc_hsc_ProductsAndServicesOnsiteServicesAndMaterialLogisticsProductQualityImprovementAndResourceRecoveryMember_67ee92cf-623f-4250-8dfb-2ca0f23e7092" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_AppliedProductsMember_0b2b210a-e9b6-4686-b220-99cbe8a69ee7" xlink:href="hsc-20211231.xsd#hsc_AppliedProductsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_e18c1c1a-4036-4f6b-b1bf-c3079d718918" xlink:to="loc_hsc_AppliedProductsMember_0b2b210a-e9b6-4686-b220-99cbe8a69ee7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_f36d1a83-07d4-4f60-9ac8-cc40a56fc865" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_b0da9918-0d76-4491-a09e-47c3124f57df" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_f36d1a83-07d4-4f60-9ac8-cc40a56fc865" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_f36d1a83-07d4-4f60-9ac8-cc40a56fc865_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_f36d1a83-07d4-4f60-9ac8-cc40a56fc865" xlink:to="loc_us-gaap_SegmentDomain_f36d1a83-07d4-4f60-9ac8-cc40a56fc865_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_d3ef32eb-077b-41fd-b51d-70cf8ecf9f97" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_f36d1a83-07d4-4f60-9ac8-cc40a56fc865" xlink:to="loc_us-gaap_SegmentDomain_d3ef32eb-077b-41fd-b51d-70cf8ecf9f97" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_CleanEarthMember_5067d547-d71a-418f-ba64-7ef3bf00d419" xlink:href="hsc-20211231.xsd#hsc_CleanEarthMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_d3ef32eb-077b-41fd-b51d-70cf8ecf9f97" xlink:to="loc_hsc_CleanEarthMember_5067d547-d71a-418f-ba64-7ef3bf00d419" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoEnvironmentalSegmentMember_50ec1997-edc2-4b1f-b507-4708bc7f752b" xlink:href="hsc-20211231.xsd#hsc_HarscoEnvironmentalSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_d3ef32eb-077b-41fd-b51d-70cf8ecf9f97" xlink:to="loc_hsc_HarscoEnvironmentalSegmentMember_50ec1997-edc2-4b1f-b507-4708bc7f752b" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/RevenueRecognitionPerformanceObligationPeriodNarrativeDetails" xlink:type="simple" xlink:href="hsc-20211231.xsd#RevenueRecognitionPerformanceObligationPeriodNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/RevenueRecognitionPerformanceObligationPeriodNarrativeDetails" xlink:type="extended" id="ieb9c2a7b64b14bb49160f26af1f5ce7b_RevenueRecognitionPerformanceObligationPeriodNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_f283ebda-401a-412e-9969-effdcbb5b9c5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_1df20630-dcf0-41ce-a49a-98a8f1b77187" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_f283ebda-401a-412e-9969-effdcbb5b9c5" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_1df20630-dcf0-41ce-a49a-98a8f1b77187" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_2e3cd230-fbb9-403c-99bc-96736082caf2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_f283ebda-401a-412e-9969-effdcbb5b9c5" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_2e3cd230-fbb9-403c-99bc-96736082caf2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_bd536f37-40cd-4669-9a08-8e05a8bb00dd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_f283ebda-401a-412e-9969-effdcbb5b9c5" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_bd536f37-40cd-4669-9a08-8e05a8bb00dd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_41f15686-3ca1-453b-ab1b-e2081bc16d2a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_bd536f37-40cd-4669-9a08-8e05a8bb00dd" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_41f15686-3ca1-453b-ab1b-e2081bc16d2a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_41f15686-3ca1-453b-ab1b-e2081bc16d2a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_41f15686-3ca1-453b-ab1b-e2081bc16d2a" xlink:to="loc_us-gaap_SegmentDomain_41f15686-3ca1-453b-ab1b-e2081bc16d2a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_467e8d51-1208-4b11-a689-e7e1ed72fa60" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_41f15686-3ca1-453b-ab1b-e2081bc16d2a" xlink:to="loc_us-gaap_SegmentDomain_467e8d51-1208-4b11-a689-e7e1ed72fa60" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoMetalsAndMineralsMember_66142b5d-a1e6-4469-bf95-39ae484759bc" xlink:href="hsc-20211231.xsd#hsc_HarscoMetalsAndMineralsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_467e8d51-1208-4b11-a689-e7e1ed72fa60" xlink:to="loc_hsc_HarscoMetalsAndMineralsMember_66142b5d-a1e6-4469-bf95-39ae484759bc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoRailMember_d4d47aa1-e405-4fb0-8dd8-3f67f0e01dc2" xlink:href="hsc-20211231.xsd#hsc_HarscoRailMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_467e8d51-1208-4b11-a689-e7e1ed72fa60" xlink:to="loc_hsc_HarscoRailMember_d4d47aa1-e405-4fb0-8dd8-3f67f0e01dc2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_dfeec7cf-9e9d-400e-a140-cc2740963bc7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_bd536f37-40cd-4669-9a08-8e05a8bb00dd" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_dfeec7cf-9e9d-400e-a140-cc2740963bc7" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/RevenueRecognitionPerformanceObligationPeriodNarrativeDetails_1" xlink:type="simple" xlink:href="hsc-20211231.xsd#RevenueRecognitionPerformanceObligationPeriodNarrativeDetails_1"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/RevenueRecognitionPerformanceObligationPeriodNarrativeDetails_1" xlink:type="extended" id="i227c7955969e4c05aa0c7b7413ae3ad9_RevenueRecognitionPerformanceObligationPeriodNarrativeDetails_1">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_f283ebda-401a-412e-9969-effdcbb5b9c5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_1df20630-dcf0-41ce-a49a-98a8f1b77187" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_f283ebda-401a-412e-9969-effdcbb5b9c5" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_1df20630-dcf0-41ce-a49a-98a8f1b77187" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_2e3cd230-fbb9-403c-99bc-96736082caf2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_f283ebda-401a-412e-9969-effdcbb5b9c5" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_2e3cd230-fbb9-403c-99bc-96736082caf2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_bd536f37-40cd-4669-9a08-8e05a8bb00dd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_f283ebda-401a-412e-9969-effdcbb5b9c5" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_bd536f37-40cd-4669-9a08-8e05a8bb00dd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_41f15686-3ca1-453b-ab1b-e2081bc16d2a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_bd536f37-40cd-4669-9a08-8e05a8bb00dd" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_41f15686-3ca1-453b-ab1b-e2081bc16d2a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_41f15686-3ca1-453b-ab1b-e2081bc16d2a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_41f15686-3ca1-453b-ab1b-e2081bc16d2a" xlink:to="loc_us-gaap_SegmentDomain_41f15686-3ca1-453b-ab1b-e2081bc16d2a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_467e8d51-1208-4b11-a689-e7e1ed72fa60" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_41f15686-3ca1-453b-ab1b-e2081bc16d2a" xlink:to="loc_us-gaap_SegmentDomain_467e8d51-1208-4b11-a689-e7e1ed72fa60" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoMetalsAndMineralsMember_66142b5d-a1e6-4469-bf95-39ae484759bc" xlink:href="hsc-20211231.xsd#hsc_HarscoMetalsAndMineralsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_467e8d51-1208-4b11-a689-e7e1ed72fa60" xlink:to="loc_hsc_HarscoMetalsAndMineralsMember_66142b5d-a1e6-4469-bf95-39ae484759bc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoRailMember_d4d47aa1-e405-4fb0-8dd8-3f67f0e01dc2" xlink:href="hsc-20211231.xsd#hsc_HarscoRailMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_467e8d51-1208-4b11-a689-e7e1ed72fa60" xlink:to="loc_hsc_HarscoRailMember_d4d47aa1-e405-4fb0-8dd8-3f67f0e01dc2" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/OtherExpensesDetails" xlink:type="simple" xlink:href="hsc-20211231.xsd#OtherExpensesDetails"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/OtherExpensesDetails" xlink:type="extended" id="i33aa1e9b65bc401396d174eecef26409_OtherExpensesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_37b9160a-97a4-4489-ad8e-b4f9bbd479c2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnDispositionOfAssets_00021cfb-1b3c-43ac-aa4b-425b6478ab43" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GainLossOnDispositionOfAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_37b9160a-97a4-4489-ad8e-b4f9bbd479c2" xlink:to="loc_us-gaap_GainLossOnDispositionOfAssets_00021cfb-1b3c-43ac-aa4b-425b6478ab43" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeveranceCosts1_c3b305e7-71ef-456f-9bb3-fbfb23302d5c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SeveranceCosts1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_37b9160a-97a4-4489-ad8e-b4f9bbd479c2" xlink:to="loc_us-gaap_SeveranceCosts1_c3b305e7-71ef-456f-9bb3-fbfb23302d5c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_BusinessExitCostsExcludingSeverance_85c790c8-09bc-4768-8b0a-0b349ba4b6e1" xlink:href="hsc-20211231.xsd#hsc_BusinessExitCostsExcludingSeverance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_37b9160a-97a4-4489-ad8e-b4f9bbd479c2" xlink:to="loc_hsc_BusinessExitCostsExcludingSeverance_85c790c8-09bc-4768-8b0a-0b349ba4b6e1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetImpairmentCharges_5756cfb2-7d1d-45d4-a2e1-477742f8d908" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AssetImpairmentCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_37b9160a-97a4-4489-ad8e-b4f9bbd479c2" xlink:to="loc_us-gaap_AssetImpairmentCharges_5756cfb2-7d1d-45d4-a2e1-477742f8d908" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationAsset1_b682e31b-8fc8-4d1f-9aa7-2ce13907f29d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationAsset1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_37b9160a-97a4-4489-ad8e-b4f9bbd479c2" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationAsset1_b682e31b-8fc8-4d1f-9aa7-2ce13907f29d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_OtherMiscellaneousIncomeExpense_88728262-5ace-4255-be07-0abc434084d7" xlink:href="hsc-20211231.xsd#hsc_OtherMiscellaneousIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_37b9160a-97a4-4489-ad8e-b4f9bbd479c2" xlink:to="loc_hsc_OtherMiscellaneousIncomeExpense_88728262-5ace-4255-be07-0abc434084d7" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_IncomeExpenseOtherNet_1b033a89-33ea-48c3-9e84-defd27945cfa" xlink:href="hsc-20211231.xsd#hsc_IncomeExpenseOtherNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_37b9160a-97a4-4489-ad8e-b4f9bbd479c2" xlink:to="loc_hsc_IncomeExpenseOtherNet_1b033a89-33ea-48c3-9e84-defd27945cfa" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_de2e9b76-943c-4978-87d8-623a804466ab" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_37b9160a-97a4-4489-ad8e-b4f9bbd479c2" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_de2e9b76-943c-4978-87d8-623a804466ab" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_7f6c034c-1fa9-4548-92dd-f6d24e3180ea" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_de2e9b76-943c-4978-87d8-623a804466ab" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_7f6c034c-1fa9-4548-92dd-f6d24e3180ea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_7f6c034c-1fa9-4548-92dd-f6d24e3180ea_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_7f6c034c-1fa9-4548-92dd-f6d24e3180ea" xlink:to="loc_us-gaap_SegmentDomain_7f6c034c-1fa9-4548-92dd-f6d24e3180ea_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_d823a75e-d819-49a2-99b6-d12b1622e72a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_7f6c034c-1fa9-4548-92dd-f6d24e3180ea" xlink:to="loc_us-gaap_SegmentDomain_d823a75e-d819-49a2-99b6-d12b1622e72a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_CleanEarthMember_1a1f32af-5f1e-4ab9-bd3b-1a62bb318f02" xlink:href="hsc-20211231.xsd#hsc_CleanEarthMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_d823a75e-d819-49a2-99b6-d12b1622e72a" xlink:to="loc_hsc_CleanEarthMember_1a1f32af-5f1e-4ab9-bd3b-1a62bb318f02" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoRailMember_cc83c29b-2260-496f-a244-47d3647ca6da" xlink:href="hsc-20211231.xsd#hsc_HarscoRailMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_d823a75e-d819-49a2-99b6-d12b1622e72a" xlink:to="loc_hsc_HarscoRailMember_cc83c29b-2260-496f-a244-47d3647ca6da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_HarscoEnvironmentalSegmentMember_76be9be0-1ab1-42c0-ba5a-efd6d6f76d68" xlink:href="hsc-20211231.xsd#hsc_HarscoEnvironmentalSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_d823a75e-d819-49a2-99b6-d12b1622e72a" xlink:to="loc_hsc_HarscoEnvironmentalSegmentMember_76be9be0-1ab1-42c0-ba5a-efd6d6f76d68" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_2becb361-954a-49cd-b418-5628534c1a5b" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_de2e9b76-943c-4978-87d8-623a804466ab" xlink:to="loc_srt_ConsolidationItemsAxis_2becb361-954a-49cd-b418-5628534c1a5b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_2becb361-954a-49cd-b418-5628534c1a5b_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_2becb361-954a-49cd-b418-5628534c1a5b" xlink:to="loc_srt_ConsolidationItemsDomain_2becb361-954a-49cd-b418-5628534c1a5b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_6a1936d1-e047-4181-a85c-64ff6040fecd" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_2becb361-954a-49cd-b418-5628534c1a5b" xlink:to="loc_srt_ConsolidationItemsDomain_6a1936d1-e047-4181-a85c-64ff6040fecd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MaterialReconcilingItemsMember_07c3ed75-25ae-43d1-b0d4-aabc5c5d6979" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MaterialReconcilingItemsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_6a1936d1-e047-4181-a85c-64ff6040fecd" xlink:to="loc_us-gaap_MaterialReconcilingItemsMember_07c3ed75-25ae-43d1-b0d4-aabc5c5d6979" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/ComponentsofAccumulatedOtherComprehensiveLossDetails" xlink:type="simple" xlink:href="hsc-20211231.xsd#ComponentsofAccumulatedOtherComprehensiveLossDetails"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/ComponentsofAccumulatedOtherComprehensiveLossDetails" xlink:type="extended" id="i9740a7280d3b4dfb8e9b7dd2725f85d9_ComponentsofAccumulatedOtherComprehensiveLossDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_e3b1dddf-49fa-4ba8-a6a2-66159c26282d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_c94572f9-429e-4568-a692-4a8f9f8989a5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AOCIAttributableToParentNetOfTaxRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_e3b1dddf-49fa-4ba8-a6a2-66159c26282d" xlink:to="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_c94572f9-429e-4568-a692-4a8f9f8989a5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_9861efde-1819-4c7b-87ed-65b81664426c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_c94572f9-429e-4568-a692-4a8f9f8989a5" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_9861efde-1819-4c7b-87ed-65b81664426c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_dc94c765-f63c-49cd-bb8e-72fc323b60f2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_c94572f9-429e-4568-a692-4a8f9f8989a5" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_dc94c765-f63c-49cd-bb8e-72fc323b60f2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_c1663a0f-e727-4ecf-8de2-61117daa2953" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_c94572f9-429e-4568-a692-4a8f9f8989a5" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_c1663a0f-e727-4ecf-8de2-61117daa2953" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_9830803d-2f13-439b-96b0-76111a928b70" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_c94572f9-429e-4568-a692-4a8f9f8989a5" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_9830803d-2f13-439b-96b0-76111a928b70" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToNoncontrollingInterest_78149c89-19ec-480f-b0a6-3cc174b95225" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_c94572f9-429e-4568-a692-4a8f9f8989a5" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToNoncontrollingInterest_78149c89-19ec-480f-b0a6-3cc174b95225" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_fa9d7d68-0631-42c5-a1ed-855004c688bf" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_c94572f9-429e-4568-a692-4a8f9f8989a5" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_fa9d7d68-0631-42c5-a1ed-855004c688bf" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_b7b7c1b6-e319-4586-b51f-a968498d086b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_b13855d7-7fa6-4062-b9cc-7839b404e7c8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_e3b1dddf-49fa-4ba8-a6a2-66159c26282d" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_b13855d7-7fa6-4062-b9cc-7839b404e7c8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_b0401d36-85dc-405e-9e2a-4d4090adab85" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_b13855d7-7fa6-4062-b9cc-7839b404e7c8" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_b0401d36-85dc-405e-9e2a-4d4090adab85" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_b0401d36-85dc-405e-9e2a-4d4090adab85_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_b0401d36-85dc-405e-9e2a-4d4090adab85" xlink:to="loc_us-gaap_EquityComponentDomain_b0401d36-85dc-405e-9e2a-4d4090adab85_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_e715d1ad-23cb-4430-b826-592ab867639c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_b0401d36-85dc-405e-9e2a-4d4090adab85" xlink:to="loc_us-gaap_EquityComponentDomain_e715d1ad-23cb-4430-b826-592ab867639c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedTranslationAdjustmentMember_9f3671de-e1ce-4621-b9f5-18c6ef96e800" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedTranslationAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_e715d1ad-23cb-4430-b826-592ab867639c" xlink:to="loc_us-gaap_AccumulatedTranslationAdjustmentMember_9f3671de-e1ce-4621-b9f5-18c6ef96e800" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember_4c82339f-6432-4a48-b46b-31ae0287a02f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_e715d1ad-23cb-4430-b826-592ab867639c" xlink:to="loc_us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember_4c82339f-6432-4a48-b46b-31ae0287a02f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_61ff2136-3958-4edf-9595-b0d97b0bacc3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_e715d1ad-23cb-4430-b826-592ab867639c" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_61ff2136-3958-4edf-9595-b0d97b0bacc3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember_f1c90c07-9808-4bf6-bbac-64bece1a6cd4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_e715d1ad-23cb-4430-b826-592ab867639c" xlink:to="loc_us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember_f1c90c07-9808-4bf6-bbac-64bece1a6cd4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_5d4fc3d3-106a-498d-a4c4-3030ecdc27c3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_e715d1ad-23cb-4430-b826-592ab867639c" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_5d4fc3d3-106a-498d-a4c4-3030ecdc27c3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_41025313-b7a0-4b35-8198-6b9cff6aea16" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_b13855d7-7fa6-4062-b9cc-7839b404e7c8" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_41025313-b7a0-4b35-8198-6b9cff6aea16" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_41025313-b7a0-4b35-8198-6b9cff6aea16_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_41025313-b7a0-4b35-8198-6b9cff6aea16" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_41025313-b7a0-4b35-8198-6b9cff6aea16_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_5eb9a6a7-6491-4c52-b5d5-6ef89a70ee8b" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_41025313-b7a0-4b35-8198-6b9cff6aea16" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_5eb9a6a7-6491-4c52-b5d5-6ef89a70ee8b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember_313fd851-9bd6-4d9b-8a61-08eae9db0ef4" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_5eb9a6a7-6491-4c52-b5d5-6ef89a70ee8b" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember_313fd851-9bd6-4d9b-8a61-08eae9db0ef4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionAdjustedBalanceMember_dcb3b929-0ed9-48d4-b87e-a11dc43517df" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionAdjustedBalanceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_5eb9a6a7-6491-4c52-b5d5-6ef89a70ee8b" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionAdjustedBalanceMember_dcb3b929-0ed9-48d4-b87e-a11dc43517df" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/ComponentsofAccumulatedOtherComprehensiveLossDetails2" xlink:type="simple" xlink:href="hsc-20211231.xsd#ComponentsofAccumulatedOtherComprehensiveLossDetails2"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/ComponentsofAccumulatedOtherComprehensiveLossDetails2" xlink:type="extended" id="i9dea670f9e4a416c8fa6788c6977d607_ComponentsofAccumulatedOtherComprehensiveLossDetails2">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeOnDerivativesLineItems_0641e68e-2b76-42ee-9432-49d4f2a68d38" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeOnDerivativesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionAndOtherPostretirementBenefitExpense_3679342d-5e61-4471-9d37-3813ed11820d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PensionAndOtherPostretirementBenefitExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeOnDerivativesLineItems_0641e68e-2b76-42ee-9432-49d4f2a68d38" xlink:to="loc_us-gaap_PensionAndOtherPostretirementBenefitExpense_3679342d-5e61-4471-9d37-3813ed11820d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_9b3b0a73-f20c-44ab-bc2a-f8e82d7587c4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeOnDerivativesLineItems_0641e68e-2b76-42ee-9432-49d4f2a68d38" xlink:to="loc_us-gaap_Revenues_9b3b0a73-f20c-44ab-bc2a-f8e82d7587c4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_084baebd-82ac-40d5-8cf8-db7ccfc5a377" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CostOfGoodsAndServicesSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeOnDerivativesLineItems_0641e68e-2b76-42ee-9432-49d4f2a68d38" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_084baebd-82ac-40d5-8cf8-db7ccfc5a377" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_b2e058c2-71fd-46d1-bd19-bd67f8b0054f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeOnDerivativesLineItems_0641e68e-2b76-42ee-9432-49d4f2a68d38" xlink:to="loc_us-gaap_InterestExpense_b2e058c2-71fd-46d1-bd19-bd67f8b0054f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax_9c196e24-fa5f-40a5-bdca-d1c442bce32f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeOnDerivativesLineItems_0641e68e-2b76-42ee-9432-49d4f2a68d38" xlink:to="loc_us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax_9c196e24-fa5f-40a5-bdca-d1c442bce32f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsAndExpenses_d944cd23-66f1-4564-81bf-4f3aa7c052d6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CostsAndExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeOnDerivativesLineItems_0641e68e-2b76-42ee-9432-49d4f2a68d38" xlink:to="loc_us-gaap_CostsAndExpenses_d944cd23-66f1-4564-81bf-4f3aa7c052d6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_540b84c5-909b-40e1-bf4f-73d8f471af41" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeOnDerivativesLineItems_0641e68e-2b76-42ee-9432-49d4f2a68d38" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_540b84c5-909b-40e1-bf4f-73d8f471af41" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_6f1e3145-5091-4b75-bf8e-0ec38c56dde7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeOnDerivativesLineItems_0641e68e-2b76-42ee-9432-49d4f2a68d38" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_6f1e3145-5091-4b75-bf8e-0ec38c56dde7" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_6c8559b4-fafa-4552-9f5e-bc661ef1606b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeOnDerivativesLineItems_0641e68e-2b76-42ee-9432-49d4f2a68d38" xlink:to="loc_us-gaap_ProfitLoss_6c8559b4-fafa-4552-9f5e-bc661ef1606b" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherOperatingIncomeExpenseNet_c4a058b5-ead5-4df4-b12c-1e2883513d07" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherOperatingIncomeExpenseNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeOnDerivativesLineItems_0641e68e-2b76-42ee-9432-49d4f2a68d38" xlink:to="loc_us-gaap_OtherOperatingIncomeExpenseNet_c4a058b5-ead5-4df4-b12c-1e2883513d07" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_91b335b7-8cd6-438d-8958-41304d3b4120" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeOnDerivativesLineItems_0641e68e-2b76-42ee-9432-49d4f2a68d38" xlink:to="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_91b335b7-8cd6-438d-8958-41304d3b4120" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis_4c1cb016-9008-4158-abd4-b169906cfcb7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_91b335b7-8cd6-438d-8958-41304d3b4120" xlink:to="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis_4c1cb016-9008-4158-abd4-b169906cfcb7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_4c1cb016-9008-4158-abd4-b169906cfcb7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis_4c1cb016-9008-4158-abd4-b169906cfcb7" xlink:to="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_4c1cb016-9008-4158-abd4-b169906cfcb7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_9a2a7099-81e1-4779-83fa-0563f892c18d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis_4c1cb016-9008-4158-abd4-b169906cfcb7" xlink:to="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_9a2a7099-81e1-4779-83fa-0563f892c18d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember_cc85eee3-1da7-4d3a-8a7a-0d8ed4c37bba" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_9a2a7099-81e1-4779-83fa-0563f892c18d" xlink:to="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember_cc85eee3-1da7-4d3a-8a7a-0d8ed4c37bba" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_23359a0c-26bd-44d7-82a1-dee1d4e6c3d3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_91b335b7-8cd6-438d-8958-41304d3b4120" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_23359a0c-26bd-44d7-82a1-dee1d4e6c3d3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_23359a0c-26bd-44d7-82a1-dee1d4e6c3d3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_23359a0c-26bd-44d7-82a1-dee1d4e6c3d3" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_23359a0c-26bd-44d7-82a1-dee1d4e6c3d3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_7aa3a4c0-c3c2-42aa-948c-430f01b293ec" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_23359a0c-26bd-44d7-82a1-dee1d4e6c3d3" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_7aa3a4c0-c3c2-42aa-948c-430f01b293ec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeForwardMember_7d9d7430-79da-4728-bfce-6b233c64c1e0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ForeignExchangeForwardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_7aa3a4c0-c3c2-42aa-948c-430f01b293ec" xlink:to="loc_us-gaap_ForeignExchangeForwardMember_7d9d7430-79da-4728-bfce-6b233c64c1e0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CrossCurrencyInterestRateContractMember_ad730e40-8f91-4e89-9796-225eef0c0bd3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CrossCurrencyInterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_7aa3a4c0-c3c2-42aa-948c-430f01b293ec" xlink:to="loc_us-gaap_CrossCurrencyInterestRateContractMember_ad730e40-8f91-4e89-9796-225eef0c0bd3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_cf4e7f3f-e28d-4c98-a061-583764b3b887" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_7aa3a4c0-c3c2-42aa-948c-430f01b293ec" xlink:to="loc_us-gaap_InterestRateSwapMember_cf4e7f3f-e28d-4c98-a061-583764b3b887" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_77f23e40-fbe2-4dfd-a1ec-5e64c93ac5c5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_91b335b7-8cd6-438d-8958-41304d3b4120" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_77f23e40-fbe2-4dfd-a1ec-5e64c93ac5c5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_77f23e40-fbe2-4dfd-a1ec-5e64c93ac5c5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_77f23e40-fbe2-4dfd-a1ec-5e64c93ac5c5" xlink:to="loc_us-gaap_EquityComponentDomain_77f23e40-fbe2-4dfd-a1ec-5e64c93ac5c5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_bb33eecb-b3ba-4e61-97c8-5564e443d3f6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_77f23e40-fbe2-4dfd-a1ec-5e64c93ac5c5" xlink:to="loc_us-gaap_EquityComponentDomain_bb33eecb-b3ba-4e61-97c8-5564e443d3f6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_73216439-b9b6-4d16-a0c7-4699879b0741" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_bb33eecb-b3ba-4e61-97c8-5564e443d3f6" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_73216439-b9b6-4d16-a0c7-4699879b0741" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_DefinedBenefitPlanPriorServiceCostsMember_d72a2278-e190-4402-a2b9-a33d0db768d8" xlink:href="hsc-20211231.xsd#hsc_DefinedBenefitPlanPriorServiceCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_73216439-b9b6-4d16-a0c7-4699879b0741" xlink:to="loc_hsc_DefinedBenefitPlanPriorServiceCostsMember_d72a2278-e190-4402-a2b9-a33d0db768d8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_SettlementCurtailmentLossesMember_d0958ba7-eebe-4754-b43b-1a7bd113c712" xlink:href="hsc-20211231.xsd#hsc_SettlementCurtailmentLossesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_73216439-b9b6-4d16-a0c7-4699879b0741" xlink:to="loc_hsc_SettlementCurtailmentLossesMember_d0958ba7-eebe-4754-b43b-1a7bd113c712" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember_e26a1a47-1339-44f6-b282-e67dce9d799e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_bb33eecb-b3ba-4e61-97c8-5564e443d3f6" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember_e26a1a47-1339-44f6-b282-e67dce9d799e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember_8f46bdc4-c8fc-449b-bfdb-86dcb7c9ebbe" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_bb33eecb-b3ba-4e61-97c8-5564e443d3f6" xlink:to="loc_us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember_8f46bdc4-c8fc-449b-bfdb-86dcb7c9ebbe" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCreditMember_dd9c1072-6b87-468f-ad03-143e529168fb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_bb33eecb-b3ba-4e61-97c8-5564e443d3f6" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCreditMember_dd9c1072-6b87-468f-ad03-143e529168fb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_c778ece6-842b-4a6f-acd7-9a312999554b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_91b335b7-8cd6-438d-8958-41304d3b4120" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_c778ece6-842b-4a6f-acd7-9a312999554b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_c778ece6-842b-4a6f-acd7-9a312999554b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_c778ece6-842b-4a6f-acd7-9a312999554b" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_c778ece6-842b-4a6f-acd7-9a312999554b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_6577c415-63ae-468d-9858-a81db70af512" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_c778ece6-842b-4a6f-acd7-9a312999554b" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_6577c415-63ae-468d-9858-a81db70af512" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDiscontinuedOperationsMember_90164654-1f20-4485-a952-62cf3b9773c2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDiscontinuedOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_6577c415-63ae-468d-9858-a81db70af512" xlink:to="loc_us-gaap_SegmentDiscontinuedOperationsMember_90164654-1f20-4485-a952-62cf3b9773c2" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/SCHEDULEIIVALUATIONANDQUALIFYINGACCOUNTSDetails" xlink:type="simple" xlink:href="hsc-20211231.xsd#SCHEDULEIIVALUATIONANDQUALIFYINGACCOUNTSDetails"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/SCHEDULEIIVALUATIONANDQUALIFYINGACCOUNTSDetails" xlink:type="extended" id="i2bbed90cf28a4e17be367486a918a935_SCHEDULEIIVALUATIONANDQUALIFYINGACCOUNTSDetails">
    <link:loc xlink:type="locator" xlink:label="loc_srt_ValuationAndQualifyingAccountsDisclosureLineItems_63ef9b56-b33f-4038-8293-23460ac14869" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ValuationAndQualifyingAccountsDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_439f2682-c94d-4b06-a9c8-9513d13fdd6a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MovementInValuationAllowancesAndReservesRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ValuationAndQualifyingAccountsDisclosureLineItems_63ef9b56-b33f-4038-8293-23460ac14869" xlink:to="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_439f2682-c94d-4b06-a9c8-9513d13fdd6a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesBalance_9dd9d31a-9bde-4404-8d22-e0ac8b1e31b0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowancesAndReservesBalance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_439f2682-c94d-4b06-a9c8-9513d13fdd6a" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesBalance_9dd9d31a-9bde-4404-8d22-e0ac8b1e31b0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense_6565d95e-7564-47a1-82d3-0903973fb564" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_439f2682-c94d-4b06-a9c8-9513d13fdd6a" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense_6565d95e-7564-47a1-82d3-0903973fb564" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesAdjustments_550de6cc-9680-45b4-a30b-d04827001600" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowancesAndReservesAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_439f2682-c94d-4b06-a9c8-9513d13fdd6a" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesAdjustments_550de6cc-9680-45b4-a30b-d04827001600" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesChargedToOtherAccounts_04864a3e-1edb-4eea-9445-784b6419ba29" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowancesAndReservesChargedToOtherAccounts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_439f2682-c94d-4b06-a9c8-9513d13fdd6a" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesChargedToOtherAccounts_04864a3e-1edb-4eea-9445-784b6419ba29" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesBalance_b84fb29c-48eb-4ea1-81cc-eec4ffc4b4be" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowancesAndReservesBalance"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_87503c45-9d95-4f92-8195-8ab451d688d2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ValuationAndQualifyingAccountsDisclosureLineItems_63ef9b56-b33f-4038-8293-23460ac14869" xlink:to="loc_us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_87503c45-9d95-4f92-8195-8ab451d688d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedEnvironmentalLossContingenciesNoncurrent_0e9d4b46-4055-43c8-a093-ddd93266835d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccruedEnvironmentalLossContingenciesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ValuationAndQualifyingAccountsDisclosureLineItems_63ef9b56-b33f-4038-8293-23460ac14869" xlink:to="loc_us-gaap_AccruedEnvironmentalLossContingenciesNoncurrent_0e9d4b46-4055-43c8-a093-ddd93266835d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ValuationAndQualifyingAccountsDisclosureTable_70625c24-5f82-4c62-b945-0c7c723212fb" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ValuationAndQualifyingAccountsDisclosureTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_srt_ValuationAndQualifyingAccountsDisclosureLineItems_63ef9b56-b33f-4038-8293-23460ac14869" xlink:to="loc_srt_ValuationAndQualifyingAccountsDisclosureTable_70625c24-5f82-4c62-b945-0c7c723212fb" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowanceByDeferredTaxAssetAxis_9693b424-0ea3-4de9-a275-ccfdc9039908" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowanceByDeferredTaxAssetAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_srt_ValuationAndQualifyingAccountsDisclosureTable_70625c24-5f82-4c62-b945-0c7c723212fb" xlink:to="loc_us-gaap_ValuationAllowanceByDeferredTaxAssetAxis_9693b424-0ea3-4de9-a275-ccfdc9039908" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetDomain_9693b424-0ea3-4de9-a275-ccfdc9039908_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ValuationAllowanceByDeferredTaxAssetAxis_9693b424-0ea3-4de9-a275-ccfdc9039908" xlink:to="loc_us-gaap_DeferredTaxAssetDomain_9693b424-0ea3-4de9-a275-ccfdc9039908_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetDomain_82233c76-3dd7-46a4-ae28-af93624f0e91" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredTaxAssetDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ValuationAllowanceByDeferredTaxAssetAxis_9693b424-0ea3-4de9-a275-ccfdc9039908" xlink:to="loc_us-gaap_DeferredTaxAssetDomain_82233c76-3dd7-46a4-ae28-af93624f0e91" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ValuationAllowanceDeferredTaxAssetliquidationandMergerofEntitiesMember_ed1fb2c2-8283-4c48-96f8-96f4b703d331" xlink:href="hsc-20211231.xsd#hsc_ValuationAllowanceDeferredTaxAssetliquidationandMergerofEntitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxAssetDomain_82233c76-3dd7-46a4-ae28-af93624f0e91" xlink:to="loc_hsc_ValuationAllowanceDeferredTaxAssetliquidationandMergerofEntitiesMember_ed1fb2c2-8283-4c48-96f8-96f4b703d331" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ValuationAllowanceDeferredTaxAssetPensionAdjustmentsMember_77781c3b-c457-4b14-b260-ff51407a5d57" xlink:href="hsc-20211231.xsd#hsc_ValuationAllowanceDeferredTaxAssetPensionAdjustmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxAssetDomain_82233c76-3dd7-46a4-ae28-af93624f0e91" xlink:to="loc_hsc_ValuationAllowanceDeferredTaxAssetPensionAdjustmentsMember_77781c3b-c457-4b14-b260-ff51407a5d57" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_TaxRateChangeMember_3ca0e4fb-63d7-4f89-878e-245b65468f18" xlink:href="hsc-20211231.xsd#hsc_TaxRateChangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxAssetDomain_82233c76-3dd7-46a4-ae28-af93624f0e91" xlink:to="loc_hsc_TaxRateChangeMember_3ca0e4fb-63d7-4f89-878e-245b65468f18" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_418a48dd-0c4c-4926-88ba-a28813d94a07" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowancesAndReservesTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_srt_ValuationAndQualifyingAccountsDisclosureTable_70625c24-5f82-4c62-b945-0c7c723212fb" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_418a48dd-0c4c-4926-88ba-a28813d94a07" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesDomain_418a48dd-0c4c-4926-88ba-a28813d94a07_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowancesAndReservesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_418a48dd-0c4c-4926-88ba-a28813d94a07" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesDomain_418a48dd-0c4c-4926-88ba-a28813d94a07_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesDomain_40b8519f-3710-4be0-b463-155effebc6cb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowancesAndReservesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_418a48dd-0c4c-4926-88ba-a28813d94a07" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesDomain_40b8519f-3710-4be0-b463-155effebc6cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForCreditLossMember_e813c2d5-1c5a-4347-adaf-0374e676d3b2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AllowanceForCreditLossMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesDomain_40b8519f-3710-4be0-b463-155effebc6cb" xlink:to="loc_us-gaap_AllowanceForCreditLossMember_e813c2d5-1c5a-4347-adaf-0374e676d3b2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember_568d40b0-5de2-4ff9-bf1c-1399fb67ac05" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesDomain_40b8519f-3710-4be0-b463-155effebc6cb" xlink:to="loc_us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember_568d40b0-5de2-4ff9-bf1c-1399fb67ac05" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowanceTaxCreditCarryforwardMember_2a37bf2f-35a5-4605-bcdc-212a4859f7f9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ValuationAllowanceTaxCreditCarryforwardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesDomain_40b8519f-3710-4be0-b463-155effebc6cb" xlink:to="loc_us-gaap_ValuationAllowanceTaxCreditCarryforwardMember_2a37bf2f-35a5-4605-bcdc-212a4859f7f9" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.harsco.com/role/SubsequentEventsDetails" xlink:type="simple" xlink:href="hsc-20211231.xsd#SubsequentEventsDetails"/>
  <link:definitionLink xlink:role="http://www.harsco.com/role/SubsequentEventsDetails" xlink:type="extended" id="i8bc39bcc4346400184d01a2e620e14ae_SubsequentEventsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventLineItems_3937955d-a9bb-451c-b913-fc324e9f6e4d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_NetDebtToConsolidatedAdjustedEBITDARatioCovenant_cff8c3ed-bb0a-4f86-b07f-55fe738f47b7" xlink:href="hsc-20211231.xsd#hsc_NetDebtToConsolidatedAdjustedEBITDARatioCovenant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_3937955d-a9bb-451c-b913-fc324e9f6e4d" xlink:to="loc_hsc_NetDebtToConsolidatedAdjustedEBITDARatioCovenant_cff8c3ed-bb0a-4f86-b07f-55fe738f47b7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_NetDebtToConsolidatedAdjustedEBITDARatioCovenantQuarterlyIncreaseDecrease_3c6b8721-c41d-458f-8589-ed2647e2da13" xlink:href="hsc-20211231.xsd#hsc_NetDebtToConsolidatedAdjustedEBITDARatioCovenantQuarterlyIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_3937955d-a9bb-451c-b913-fc324e9f6e4d" xlink:to="loc_hsc_NetDebtToConsolidatedAdjustedEBITDARatioCovenantQuarterlyIncreaseDecrease_3c6b8721-c41d-458f-8589-ed2647e2da13" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_NetDebtToConsolidatedAdjustedEBITDARatioCovenantIncreaseDecreaseRelatedToDivestureOfBusiness_ebfd739b-c6e1-4797-813f-31848efe22e2" xlink:href="hsc-20211231.xsd#hsc_NetDebtToConsolidatedAdjustedEBITDARatioCovenantIncreaseDecreaseRelatedToDivestureOfBusiness"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_3937955d-a9bb-451c-b913-fc324e9f6e4d" xlink:to="loc_hsc_NetDebtToConsolidatedAdjustedEBITDARatioCovenantIncreaseDecreaseRelatedToDivestureOfBusiness_ebfd739b-c6e1-4797-813f-31848efe22e2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_hsc_ThresholdNetDebtToConsolidatedAdjustedEBITDARatioCovenant_62fd0ac0-9eba-404e-a61d-76e87c718aee" xlink:href="hsc-20211231.xsd#hsc_ThresholdNetDebtToConsolidatedAdjustedEBITDARatioCovenant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_3937955d-a9bb-451c-b913-fc324e9f6e4d" xlink:to="loc_hsc_ThresholdNetDebtToConsolidatedAdjustedEBITDARatioCovenant_62fd0ac0-9eba-404e-a61d-76e87c718aee" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTable_ddf50a63-0aa7-4afc-8f8c-d6928815ba62" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_3937955d-a9bb-451c-b913-fc324e9f6e4d" xlink:to="loc_us-gaap_SubsequentEventTable_ddf50a63-0aa7-4afc-8f8c-d6928815ba62" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_a061cb5d-456e-4c71-8170-ff7d82b04e91" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_ddf50a63-0aa7-4afc-8f8c-d6928815ba62" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_a061cb5d-456e-4c71-8170-ff7d82b04e91" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_a061cb5d-456e-4c71-8170-ff7d82b04e91_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_a061cb5d-456e-4c71-8170-ff7d82b04e91" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_a061cb5d-456e-4c71-8170-ff7d82b04e91_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_b259f196-f352-4c9a-9121-08327764cb55" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_a061cb5d-456e-4c71-8170-ff7d82b04e91" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_b259f196-f352-4c9a-9121-08327764cb55" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_e57d18ad-a735-4f7f-b310-0ff6311b8efe" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_b259f196-f352-4c9a-9121-08327764cb55" xlink:to="loc_us-gaap_SubsequentEventMember_e57d18ad-a735-4f7f-b310-0ff6311b8efe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_95946e7c-ac58-4e9e-b222-74d08ae1fcad" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_ddf50a63-0aa7-4afc-8f8c-d6928815ba62" xlink:to="loc_srt_StatementScenarioAxis_95946e7c-ac58-4e9e-b222-74d08ae1fcad" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_95946e7c-ac58-4e9e-b222-74d08ae1fcad_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_95946e7c-ac58-4e9e-b222-74d08ae1fcad" xlink:to="loc_srt_ScenarioUnspecifiedDomain_95946e7c-ac58-4e9e-b222-74d08ae1fcad_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_66191186-4ec0-49d7-abe8-72cc84f8bebb" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_95946e7c-ac58-4e9e-b222-74d08ae1fcad" xlink:to="loc_srt_ScenarioUnspecifiedDomain_66191186-4ec0-49d7-abe8-72cc84f8bebb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioForecastMember_53a7dea8-753c-4798-a815-61959850e38c" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ScenarioForecastMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ScenarioUnspecifiedDomain_66191186-4ec0-49d7-abe8-72cc84f8bebb" xlink:to="loc_srt_ScenarioForecastMember_53a7dea8-753c-4798-a815-61959850e38c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_7386b2d1-d542-4304-9948-ff1f2e561be7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_ddf50a63-0aa7-4afc-8f8c-d6928815ba62" xlink:to="loc_us-gaap_CreditFacilityAxis_7386b2d1-d542-4304-9948-ff1f2e561be7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_7386b2d1-d542-4304-9948-ff1f2e561be7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_7386b2d1-d542-4304-9948-ff1f2e561be7" xlink:to="loc_us-gaap_CreditFacilityDomain_7386b2d1-d542-4304-9948-ff1f2e561be7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_bcc8b7d8-a4db-43d8-b321-1152be6bb9c0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_7386b2d1-d542-4304-9948-ff1f2e561be7" xlink:to="loc_us-gaap_CreditFacilityDomain_bcc8b7d8-a4db-43d8-b321-1152be6bb9c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_9c6ab84f-1a14-45b6-bd95-1bd141e126b0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_bcc8b7d8-a4db-43d8-b321-1152be6bb9c0" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_9c6ab84f-1a14-45b6-bd95-1bd141e126b0" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fasb.org/us-gaap/role/eedm/ExtensibleEnumerationLists" xlink:type="simple" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-roles-2021-01-31.xsd#eedm"/>
  <link:definitionLink xlink:role="http://fasb.org/us-gaap/role/eedm/ExtensibleEnumerationLists" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AssetsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrentAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LiabilitiesCurrentAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermDebtCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract" xlink:to="loc_us-gaap_LongTermDebtCurrent" xlink:type="arc" order="0"/>
  </link:definitionLink>
</link:linkbase>
