Source : Webster's Revised Unabridged Dictionary (1913)

Ulna \Ul"na\, n. [L., the elbow. See {Ell}.]
   1. (Anat.) The postaxial bone of the forearm, or branchium,
      corresponding to the fibula of the hind limb. See
      {Radius}.

   2. (O. Eng. Law) An ell; also, a yard. --Burrill.

Source : WordNet®

ulna
     n : the inner and longer of the two bones of the human forearm
         [syn: {elbow bone}]
     [also: {ulnae} (pl)]