Where does “in-” come from?

in- (Middle English) comes from Old English in-, from Old English in, from Proto-West Germanic *in, from Proto-Germanic in, from Proto-Indo-European én — in.

Ancestry of “in-”, step by step

StepLanguageWordMeaning
1Old Englishin-in, into; on, upon; internal, positioned on the...
2Old Englishinin; Alternative form of inn
3Proto-West Germanic*in—
4Proto-Germanicinin; into
5Proto-Indo-Europeanénin

Words derived from “in-”

Every word from Proto-Indo-European én →Every word from Proto-Germanic in →Every word from Proto-West Germanic *in →