"a dividing into portions or shares," 1620s, from apportion + -ment. Perhaps influenced by French apportionnement. In U.S. especially of distribution of seats in the House of Representatives.
the apportionment of seats in the House of Representatives is based on the relative population of each state
appointed
appointee
appointment
Appomattox
apportion
apportionment
appose
apposite
apposition
appositive
appraisal