cayuse ((n.)) [< the Cayuse Indians of parts of Washington and Oregon, U.S.A.] DCHP-1 (pre-1967)
n.
Originally, a wild pony, a mustang; later generalized in the West as a name for any horse, often with a derogatory or contemptuous connotation.
See also: Indian horse Indian pony shaganappi pony squaw horse