phalanx vs os

phalanx and os both are nouns.

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

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

Other hypernyms of phalanx include bone.

phalanx (noun)	os (noun)
any of the bones of the fingers or toes	rigid connective tissue that makes up the skeleton of vertebrates
a body of troops in close array	a mouth or mouthlike opening
any closely ranked crowd of people