eccentric vs adult

eccentric and adult both are nouns.

Word	Noun	Adjective	Verb	Adverb
eccentric	Yes	Yes	No	No
adult	Yes	Yes	No	No

As nouns, adult is a hypernym of eccentric; that is, adult is a word with a broader meaning than eccentric:

Other hypernyms of eccentric include grownup.

eccentric (noun)	adult (noun)
a person with an unusual or odd personality	any mature animal
a person of a specified kind (usually with many eccentricities)	a fully developed person from maturity onward

eccentric (adjective)	adult (adjective)
not having a common center; not concentric	(of animals) fully developed
conspicuously or grossly unconventional or unusual	designed to arouse lust