(1):

(a.) Of or pertaining to horses or horsemen, or to horsemanship; as, equestrian feats, or games.

(2):

(a.) Belonging to, or composed of, the ancient Roman equities or knights; as, the equestrian order.

(3):

(n.) One who rides on horseback; a horseman; a rider.

(4):

(a.) Being or riding on horseback; mounted; as, an equestrian statue.