sinus vs cavum

sinus and cavum both are nouns.

Word	Noun	Adjective	Verb	Adverb
sinus	Yes	No	No	No
cavum	Yes	No	No	No

As nouns, cavum is a hypernym of sinus; that is, cavum is a word with a broader meaning than sinus:

sinus: any of various air-filled cavities especially in the bones of the skull
cavum: (anatomy) a natural hollow or sinus within the body

Other hypernyms of sinus include bodily cavity, cavity.

sinus (noun)	cavum (noun)
a wide channel containing blood; does not have the coating of an ordinary blood vessel	(anatomy) a natural hollow or sinus within the body
any of various air-filled cavities especially in the bones of the skull
an abnormal passage leading from a suppurating cavity to the body surface