The Collaborative International Dictionary of English v.0.48:
knucks \knucks\ n. pl. same as knuckles. Syn: brass knucks, brass knuckles, knuckles, knuckle duster. [WordNet 1.5]WordNet (r) 3.0 (2006):
knucks n 1: a small metal weapon; worn over the knuckles on the back of the hand [syn: brass knucks, knucks, brass knuckles, knuckles, knuckle duster]