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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019cba9b-00af-769a-9803-871a517eda90,g:1cf06f37-56a8-4f21-8c77-6b693f2dd41f-->
<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://xbrl.sec.gov/ecd/role/PvpAdjustmentsOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2025/ecd-2025.xsd#PvpAdjustmentsOnly"/>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/ecd/role/PvpAdjustmentsOnly" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ecd_AllAdjToCompMember" xlink:href="https://xbrl.sec.gov/ecd/2025/ecd-2025.xsd#ecd_AllAdjToCompMember"/>
    <link:loc xlink:type="locator" xlink:label="loc_ffs_AdjustmentToTheAmountsReportedInTheSummaryCompensationTableAsStockAwardsAndOptionAwardsGrantedDuringTheYearWhichAreBasedOnGrantDateFairValuesMember_019cba9b-00af-75d8-becc-0b23fd0ac090" xlink:href="ffs-20260306.xsd#ffs_AdjustmentToTheAmountsReportedInTheSummaryCompensationTableAsStockAwardsAndOptionAwardsGrantedDuringTheYearWhichAreBasedOnGrantDateFairValuesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllAdjToCompMember" xlink:to="loc_ffs_AdjustmentToTheAmountsReportedInTheSummaryCompensationTableAsStockAwardsAndOptionAwardsGrantedDuringTheYearWhichAreBasedOnGrantDateFairValuesMember_019cba9b-00af-75d8-becc-0b23fd0ac090" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ffs_AdjustmentToFairValueOfEquityAwardsGrantedDuringTheYearWhichRemainOutstandingAndUnvestedAtTheEndOfTheYearMember_019cba9b-00af-70e7-a7f8-9025d9f4b271" xlink:href="ffs-20260306.xsd#ffs_AdjustmentToFairValueOfEquityAwardsGrantedDuringTheYearWhichRemainOutstandingAndUnvestedAtTheEndOfTheYearMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllAdjToCompMember" xlink:to="loc_ffs_AdjustmentToFairValueOfEquityAwardsGrantedDuringTheYearWhichRemainOutstandingAndUnvestedAtTheEndOfTheYearMember_019cba9b-00af-70e7-a7f8-9025d9f4b271" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ffs_AdjustmentToAwardsGrantedInPriorYearsThatRemainOutstandingAndUnvestedDuringTheYearMember_019cba9b-00af-7625-b82a-c3c44a1838e1" xlink:href="ffs-20260306.xsd#ffs_AdjustmentToAwardsGrantedInPriorYearsThatRemainOutstandingAndUnvestedDuringTheYearMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllAdjToCompMember" xlink:to="loc_ffs_AdjustmentToAwardsGrantedInPriorYearsThatRemainOutstandingAndUnvestedDuringTheYearMember_019cba9b-00af-7625-b82a-c3c44a1838e1" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_ffs_AdjustmentToAwardsGrantedInPriorYearsVestedDuringTheYearMember_019cba9b-00af-7c41-9e9a-8710eb7edbc9" xlink:href="ffs-20260306.xsd#ffs_AdjustmentToAwardsGrantedInPriorYearsVestedDuringTheYearMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllAdjToCompMember" xlink:to="loc_ffs_AdjustmentToAwardsGrantedInPriorYearsVestedDuringTheYearMember_019cba9b-00af-7c41-9e9a-8710eb7edbc9" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_ffs_AdjustmentToActuarialPresentValueOfAccumulatedDefinedPensionBenefitMember_019cba9b-00af-7995-bbdd-c99debc1bd9e" xlink:href="ffs-20260306.xsd#ffs_AdjustmentToActuarialPresentValueOfAccumulatedDefinedPensionBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllAdjToCompMember" xlink:to="loc_ffs_AdjustmentToActuarialPresentValueOfAccumulatedDefinedPensionBenefitMember_019cba9b-00af-7995-bbdd-c99debc1bd9e" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_ffs_AdjustmentToStockAwardsAndOptionAwardsGrantedDuringTheYearMember_019cba9b-00af-7980-9b9e-6f51230a9a33" xlink:href="ffs-20260306.xsd#ffs_AdjustmentToStockAwardsAndOptionAwardsGrantedDuringTheYearMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllAdjToCompMember" xlink:to="loc_ffs_AdjustmentToStockAwardsAndOptionAwardsGrantedDuringTheYearMember_019cba9b-00af-7980-9b9e-6f51230a9a33" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_ffs_AdjustmentToEquityAwardsGrantedDuringTheYearWhichRemainOutstandingAndUnvestedMember_019cba9b-00af-7763-8b24-e9eed738c796" xlink:href="ffs-20260306.xsd#ffs_AdjustmentToEquityAwardsGrantedDuringTheYearWhichRemainOutstandingAndUnvestedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllAdjToCompMember" xlink:to="loc_ffs_AdjustmentToEquityAwardsGrantedDuringTheYearWhichRemainOutstandingAndUnvestedMember_019cba9b-00af-7763-8b24-e9eed738c796" xlink:type="arc" order="10"/>
  </link:definitionLink>
</link:linkbase>
