Where does “ingenuous” come from?

Ingenuous comes from Latin ingenuus, formed from the prefix in- and the root ingenuus, ultimately deriving from Proto-Indo-European ne and h₁én.

ingenuous (English): Naive and trusting; Demonstrating childlike...

Definitions

Step	Language	Word	Meaning
1	Latin	ingenuus	natural, indigenous; freeborn; noble, upright,...
2	Latin	in-	un-, non-, not; in, within, inside
3	Latin	in	in, at, on, upon, from; within, while in; into,...
4	Old Latin	en	in
5	Proto-Italic	en	in
6	Proto-Indo-European	h₁én	in

ingenuous — Etymology, Origin & Word History | Etymology Explorer