"trifle, knick-knack," by c. 1820, earlier "mechanical contrivance" (1630s), originally "showy person" (1610s), of uncertain origin. Perhaps an alteration of Middle English gibecrake, the name of some kind of ornament on wooden furniture (mid-14c.), which is perhaps from Old French giber "to rattle, shake" + some special sense of Middle English crak "sharp noise, crack." In 18c.-19c. gimcrack also could mean "person who has a turn for mechanical contrivances."
