obligated vs tributary

obligated is not a noun while tributary is a noun.

Word	Noun	Adjective	Verb	Adverb
obligated	No	Yes	No	No
tributary	Yes	Yes	No	No

obligated (noun)	tributary (noun)
	a branch that flows into the main stream

obligated (adjective)	tributary (adjective)
caused by law or conscience to follow a certain course	tending to bring about; being partly responsible for
	paying tribute
	(of a stream) flowing into a larger stream