extensor vs quad

extensor and quad both are nouns.

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

As nouns, quad is a hyponym of extensor; that is, quad is a word with a more specific, narrower meaning than extensor:

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

Other hyponyms of extensor include musculus quadriceps femoris, quadriceps, quadriceps femoris.

extensor (noun)	quad (noun)
a skeletal muscle whose contraction extends or stretches a body part	a rectangular area surrounded on all sides by buildings
	(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