early 15c., from Latin approximatus, past participle of approximare "to come near to," from ad- "to" (see ad-) + proximare "come near," from proximus "nearest," superlative of prope "near" (see propinquity).

early 15c., "to bring or put close," from approximate, adj.. Meaning "to come close" is from 1789. Related: Approximated; approximating.