Source : Webster's Revised Unabridged Dictionary (1913)

Pastern \Pas"tern\, n. [Of. pasturon, F. p[^a]turon, fr. OF.
   pasture a tether, for beasts while pasturing; prop., a
   pasturing. See {Pasture}.]
   1. The part of the foot of the horse, and allied animals,
      between the fetlock and the coffin joint. See Illust. of
      {Horse}.

   Note: The upper bone, or phalanx, of the foot is called the
         {great pastern bone}; the second, the {small pastern
         bone}; and the third, in the hoof, the {coffin bone}.

   {Pastern joint}, the joint in the hoof of the horse, and
      allied animals, between the great and small pastern bones.

   2. A shackle for horses while pasturing. --Knight.

   3. A patten. [Obs.] --Dryden.

Source : WordNet®

pastern
     n : the part between the fetlock and the hoof [syn: {fetter bone}]