Crup″per (kr?p″p?r in U.S.; kr?p″?r in Eng.), n. [F. croupi�re, fr. croupe. See Croup the rump of a horse.] [Written also crouper.] 1. The buttocks or rump of a horse.
2. A leather loop, passing under a horse's tail, and buckled to the saddle to keep it from slipping forwards.