fabella

noun
fa·​bel·​la | \ fə-ˈbel-ə How to pronounce fabella (audio) \
plural fabellae\ -​ˈbel-​ˌē How to pronounce fabellae (audio) \

Medical Definition of fabella

: a small fibrocartilage ossified in many animals and sometimes in humans in the tendon of the gastrocnemius muscle, behind one or both of the femoral condyles