c. 1300, "to make (someone) an heir" (a sense now obsolete), from Old French enheriter "make heir, attribute the right of inheretance to, appoint as heir," from Late Latin inhereditare "to appoint as heir," from in- "in" (from PIE root *en "in") + Latin hereditare "to inherit," from heres (genitive heredis) "heir" (see heredity).
Sense of "receive inheritance, get by succession as representative of the former possessor" is attested from mid-14c.; in Medieval Latin inhereditare also had taken on a sense "put in possession." Original sense is retained in disinherit. Related: Inherited; inheriting; inheritable.