astronomy vs nebulous

astronomy is a noun but nebulous is not a noun.

Word	Noun	Adjective	Verb	Adverb
astronomy	Yes	No	No	No
nebulous	No	Yes	No	No

astronomy (noun)	nebulous (noun)
the branch of physics that studies celestial bodies and the universe as a whole

astronomy (adjective)	nebulous (adjective)
	of or relating to or resembling a nebula
	lacking definition or definite content
	lacking definite form or limits