/pas"teuhrn/ , n.
1. the part of the foot of a horse, cow, etc., between the fetlock and the hoof. See diag. under horse .
2. either of the two bones of this part, the upper or first phalanx (great pastern bone) and the lower or second phalanx (small pastern bone) , between which is a joint (pastern joint) .
[ 1300-50; ME pastron shackle, prob. same word as MF pasturon, pastern pastoria herding (see PASTOR, -IA) + MF -on n. suffix ]