patella vs kneepan

patella and kneepan both are nouns.

Word	Noun	Adjective	Verb	Adverb
patella	Yes	No	No	No
kneepan	Yes	No	No	No

As nouns, patella and kneepan are synonyms defined as:

patella and kneepan: a small flat triangular bone in front of the knee that protects the knee joint

Other synonyms of patella include kneecap.

patella (noun)	kneepan (noun)
a small flat triangular bone in front of the knee that protects the knee joint	a small flat triangular bone in front of the knee that protects the knee joint