The Collaborative International Dictionary of English v.0.48:

Pisiform \Pi"si*form\, a. [L. pisum a pea + -form: cf. F.
   pisiforme.]
   Resembling a pea or peas in size and shape; as, a pisiform
   iron ore.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Pisiform \Pi"si*form\, n. (Anat.)
   A small bone on the ulnar side of the carpus in man and many
   mammals. See Illust. of Artiodactyla.
   [1913 Webster]

WordNet (r) 3.0 (2006):

pisiform
    n 1: a small wrist bone that articulates only with the
         triquetral [syn: pisiform, pisiform bone, os
         pisiforme]