The bone forming the top of the knee, forming the flat covering of the joint; called the patella.

ETYM Latin, a small pan, the kneepan, dim. of patina, patena, a pan, dish.
A small flat triangular bone in front of the knee that protects the knee joint; SYN. kneecap, kneepan.
Or kneecap; Flat bone embedded in the knee tendon of birds and mammals, which protects the joint from injury.