n. One who rides on horseback; a horseman; a rider. [ 1913 Webster ]
a. [ L. equester, from eques horseman, fr. equus horse: cf. F. équestre. See Equine. ]
An equestrian lady appeared upon the plains. Spectator. [ 1913 Webster ]
n. The art of riding on horseback; performance on horseback; horsemanship;