ethmoid vs os

ethmoid and os both are nouns.

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

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

ethmoid: one of the eight bones of the cranium; a small bone filled with air spaces that forms part of the eye sockets and the nasal cavity
os: rigid connective tissue that makes up the skeleton of vertebrates

Other hypernyms of ethmoid include bone.

ethmoid (noun)	os (noun)
one of the eight bones of the cranium; a small bone filled with air spaces that forms part of the eye sockets and the nasal cavity	rigid connective tissue that makes up the skeleton of vertebrates
	a mouth or mouthlike opening