"that ridicules or mimics," 1520s, present-participle adjective from mock (v.). Related: Mockingly.

also mocking-bird, passerine bird of the southerly parts of the U.S., noted for the song of the males and its skill in imitation, 1670s (mock-bird is from 1640s), from present-participle adjective of mock (v.) + bird (n.1).

[I]t is the most famous songster of America, and is much prized as a cage-bird. Its proper song is of remarkable compass and variety, and besides this the bird has a wonderful range, being able to imitate almost any voice or even mere noises. [Century Dictionary]

"one who scorns or ridicules others," late 15c., mokker, agent noun from mock (v.).

early 15c., mokkerie, "act of derision or scorn; ridicule, disparagement; a delusion, sham, pretense," from Old French mocquerie "sneering, mockery, sarcasm" (13c., Modern French moquerie), from moquer (see mock (v.)). From mid-15c. as "joking, making mischievous pleasantries." Mockage also was common 16c.-17c.

also mockup, "model, simulation" 1919, perhaps World War I, from the verbal phrase mock up "make an experimental model" (1911), from mock (v.) + up (adv.).