Where does “en-” come from?

en- (French) comes from Old French en-, from Latin īn-, from Latin în, from Latin en, from Proto-Italic en, from Proto-Indo-European h₁én — in.

en- (French): en- all meanings

Definitions

Step	Language	Word	Meaning
1	Old French	en-	en- in; into
2	Latin	īn-	un-, non-, not
3	Latin	în	in, at, on, upon, from (space)
4	Latin	en	lookǃ beholdǃ; reallyǃ?; come onǃ
5	Proto-Italic	en	in
6	Proto-Indo-European	h₁én	in