mortise joint vs ankle

mortise joint and ankle both are nouns.

Word	Noun	Adjective	Verb	Adverb
mortise joint	Yes	No	No	No
ankle	Yes	No	No	No

As nouns, mortise joint and ankle are synonyms defined as:

mortise joint and ankle: a gliding joint between the distal ends of the tibia and fibula and the proximal end of the talus

Other synonyms of mortise joint include ankle joint, articulatio talocruralis.

mortise joint (noun)	ankle (noun)
a joint made by inserting tenon on one piece into mortise holes in the other	a gliding joint between the distal ends of the tibia and fibula and the proximal end of the talus
a gliding joint between the distal ends of the tibia and fibula and the proximal end of the talus