flunk (v.)Related entries & more
1823, American English college slang, original meaning "to back out, give up, fail," of obscure origin, traditionally said to be an alteration of British university slang funk "to be frightened, shrink from" (see funk (n.1)). Meaning "cause to fail, give a failing mark to" is from 1843. Related: Flunked; flunking.
flunky (n.)Related entries & more
also flunkey, 1782, Scottish dialect, "footman, liveried servant," of uncertain origin, perhaps a diminutive variant of flanker (in reference to servants running alongside coaches; compare footman). Sense of "flatterer, toady" first recorded 1855. "Recent in literature, but prob. much older in colloquial speech" [Century Dictionary].