nasal vs os

nasal and os both are nouns.

Word	Noun	Adjective	Verb	Adverb
nasal	Yes	Yes	No	No
os	Yes	No	No	No

As nouns, os is a hypernym of nasal; that is, os is a word with a broader meaning than nasal:

Other hypernyms of nasal include bone.

nasal (noun)	os (noun)
an elongated rectangular bone that forms the bridge of the nose	rigid connective tissue that makes up the skeleton of vertebrates
a consonant produced through the nose with the mouth closed	a mouth or mouthlike opening

nasal (adjective)	os (adjective)
of or in or relating to the nose
sounding as if the nose were pinched