1865, originally, and usually, figurative: "sour, harsh, severe" (of speech, manners, etc.), from Latin acerbus "harsh to the taste, sharp, bitter, sour," especially of unripe fruits, etc., also figuratively, of character, conduct, etc. (see acerbity) + -ic. The earlier adjective was simply acerb (1650s), from French acerbe, from Latin acerbus.