quad vs extensor muscle

quad and extensor muscle both are nouns.

Word	Noun	Adjective	Verb	Adverb
quad	Yes	No	No	No
extensor muscle	Yes	No	No	No

As nouns, extensor muscle is a hypernym of quad; that is, extensor muscle is a word with a broader meaning than quad:

quad: a muscle of the thigh that extends the leg
extensor muscle: a skeletal muscle whose contraction extends or stretches a body part

Other hypernyms of quad include extensor.

quad (noun)	extensor muscle (noun)
a rectangular area surrounded on all sides by buildings	a skeletal muscle whose contraction extends or stretches a body part
(printing) a block of type without a raised letter; used for spacing between words or sentences
a muscle of the thigh that extends the leg
one of four children born at the same time from the same pregnancy