1570s, "action of allotting," from French allotement, from Old French aloter "divide by lots" (see allot). Or else a native formation from allot + -ment. Meaning "that which is allotted, portion assigned to someone or some purpose" is from 1670s.
allopath
allopathic
allopathy
allot
allotheism
allotment
allotrope
allotropy
all-over
allow
allowable