"to raise frivolous objections, find fault without good reason," 1540s, from French caviller "to mock, jest," from Latin cavillari "to jeer, mock; satirize, argue scoffingly" (also source of Italian cavillare, Spanish cavilar), from cavilla "jest, jeering," which is related to calumnia "slander, false accusation" (see calumny). Related: Caviller, cavilling.
Meaning "to put or shift off (something) by pretense" is from 1650s; to fob (someone) off "put him off deceitfully" is from 1590s. Related: Fobbed; fobbing.
mid-15c., mokken, "make fun of," also "to trick, delude, make a fool of; treat with scorn, treat derisively or contemptuously;" from Old French mocquer "deride, jeer," a word of unknown origin. Perhaps from Vulgar Latin *muccare "to blow the nose" (as a derisive gesture), from Latin mucus; or possibly from Middle Dutch mocken "to mumble" or Middle Low German mucken "grumble." Perhaps ultimately it is imitative of such speech. Related: Mocked; mocking. Replaced Old English bysmerian. The sense of "imitate, simulate, resemble closely" (1590s, as in mockingbird ; also see mock (adj.)) is from the notion of derisive imitation.