os longum vs os

os longum and os both are nouns.

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

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

os longum: in limbs of vertebrate animals: a long cylindrical bone that contains marrow
os: rigid connective tissue that makes up the skeleton of vertebrates

Other hypernyms of os longum include bone.

os longum (noun)	os (noun)
in limbs of vertebrate animals: a long cylindrical bone that contains marrow	rigid connective tissue that makes up the skeleton of vertebrates
	a mouth or mouthlike opening