os vs marrow

os and marrow both are nouns.

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

os (noun)	marrow (noun)
rigid connective tissue that makes up the skeleton of vertebrates	the fatty network of connective tissue that fills the cavities of bones
a mouth or mouthlike opening	the choicest or most essential or most vital part of some idea or experience
	large elongated squash with creamy to deep green skins
	very tender and very nutritious tissue from marrowbones
	any of various squash plants grown for their elongated fruit with smooth dark green skin and whitish flesh