human knee vs ginglymus

human knee and ginglymus both are nouns.

Word	Noun	Adjective	Verb	Adverb
human knee	Yes	No	No	No
ginglymus	Yes	No	No	No

As nouns, ginglymus is a hypernym of human knee; that is, ginglymus is a word with a broader meaning than human knee:

human knee: hinge joint in the human leg connecting the tibia and fibula with the femur and protected in front by the patella
ginglymus: a freely moving joint in which the bones are so articulated as to allow extensive movement in one plane

Other hypernyms of human knee include ginglymoid joint, hinge joint.

human knee (noun)	ginglymus (noun)
hinge joint in the human leg connecting the tibia and fibula with the femur and protected in front by the patella	a freely moving joint in which the bones are so articulated as to allow extensive movement in one plane