Source : Webster's Revised Unabridged Dictionary (1913)

Kneepan \Knee"pan`\, n. (Anat.)
   A roundish, flattened, sesamoid bone in the tendon in front
   of the knee joint; the patella; the kneecap.

Source : WordNet®

kneepan
     n : a small flat triangular bone in front of the knee that
         protects the knee joint [syn: {patella}, {kneecap}]