anklebone vs os

anklebone and os both are nouns.

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

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

anklebone: the bone in the ankle that articulates with the leg bones to form the ankle joint
os: rigid connective tissue that makes up the skeleton of vertebrates

Other hypernyms of anklebone include bone.

anklebone (noun)	os (noun)
the bone in the ankle that articulates with the leg bones to form the ankle joint	rigid connective tissue that makes up the skeleton of vertebrates
	a mouth or mouthlike opening