cavity vs complex body part

cavity and complex body part both are nouns.

Word	Noun	Adjective	Verb	Adverb
cavity	Yes	No	No	No
complex body part	Yes	No	No	No

As nouns, complex body part is a hypernym of cavity; that is, complex body part is a word with a broader meaning than cavity:

cavity: (anatomy) a natural hollow or sinus within the body
complex body part: a particular complex anatomical part of a living thing and its construction and arrangement

Other hypernyms of cavity include anatomical structure, bodily structure, body structure, structure.

cavity (noun)	complex body part (noun)
(anatomy) a natural hollow or sinus within the body	a particular complex anatomical part of a living thing and its construction and arrangement
a sizeable hole (usually in the ground)
soft decayed area in a tooth; progressive decay can lead to the death of a tooth
space that is surrounded by something