n. That which knacks or knocks; in the plural, two pieces of wood or bone used as a plaything by boys, who strike them together by moving the hand; castanets; bones.n. A maker of knacks, toys, or small work.n. A collar- and harness-maker, employed chiefly by farmers.n. Acolliers' horse.n. One whose occupation is the slaughtering of diseased or useless horses; also, one who deals in such horses, whether for use or slaughter.n. A man who dismantles and sells the materials of old houses, ships, etc.