triceps
    n 1: any skeletal muscle having three origins (but especially
         the triceps brachii)

Triceps \Tri"ceps\, n. [NL., fr. L. triceps, having three beads;
   tres, tria, three + caput head: cf. F. triceps. See Three,
   and Chief.] (Anat.)
   A muscle having three heads; specif., the great extensor of
   the forearm, arising by three heads and inserted into the
   olecranon at the elbow.
   [1913 Webster]