The Collaborative International Dictionary of English v.0.48:
Sprocket wheel \Sprock"et wheel`\ (spr[o^]k"[e^]t hw[=e]l`). [Etymology of sprocket is uncertain.] (Mach.) Same as Chain wheel. [1913 Webster]WordNet (r) 3.0 (2006):
sprocket wheel n 1: thin wheel with teeth that engage with a chain [syn: sprocket, sprocket wheel]