olecranon(n = noun.body) olecranon process - process of the ulna that forms the outer bump of the elbow and fits into the fossa of the humerus when the arm is extended;
is a kind of appendage, outgrowth, process
is a part of elbow bone, ulna

   The large process at the proximal end of the ulna which projects behind the articulation with the humerus and forms the bony prominence of the elbow. [1913 Webster]

olecranon, n. a bony prominence on the upper end of the ulna at the elbow.

Etymology:
Gk ole(no)kranon f. olene elbow + kranion head

olecranon process