fruitcake vs eccentric

fruitcake and eccentric both are nouns.

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

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

Other hypernyms of fruitcake include eccentric person, flake, geek, oddball.

fruitcake (noun)	eccentric (noun)
a rich cake containing dried fruit and nuts and citrus peel and so on	a person with an unusual or odd personality
a whimsically eccentric person	a person of a specified kind (usually with many eccentricities)

fruitcake (adjective)	eccentric (adjective)
	not having a common center; not concentric
	conspicuously or grossly unconventional or unusual