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: Webster's Revised Unabridged Dictionary (1913)