[pas.tern] n [MF pasturon, fr. pasture tether attached to a horse's foot, alter. of (assumed) OF pastoire, fr. ML pastoria, fr. L, fem. of pastorius of a herdsman, fr. pastor herdsman--more at pastor] (ca. 1530) 1: a part of the foot of an equine extending from the fetlock to the top of the hoof--see horse illustration
2: a part of the leg of an animal other than an equine that corresponds to the pastern