early 15c., "relating to the body humors," a native formation from humor (n.), or else from Middle French humoreux "damp," from Old French humor. In Shakespeare also "whimsical, full of fancies" (1580s); "ill-humored, peevish, moody" (c. 1600). The meaning "funny, exciting laughter" dates from 1705 in English. Related: Humorously; humorousness.