benign

From Middle English benigne, borrowed from Old French benigne, from Latin benignus, meaning 'kind, good.' Latin built that word from bene ('well') plus genus ('origin, kind').

The facts don't detail a specific shift in meaning — the word has carried the sense of 'kind, good' from Latin through Old French and Middle English into modern English.

Its opposite, malign, is built the same way but with the Latin prefix for 'bad' instead of 'well' — the two words are mirror images of each other.