nebulous vs nebula

nebulous is not a noun while nebula is a noun.

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

nebulous (noun)	nebula (noun)
	(pathology) a faint cloudy spot on the cornea
	an immense cloud of gas (mainly hydrogen) and dust in interstellar space
	cloudiness of the urine
	a medicinal liquid preparation intended for use in an atomizer

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