fastidiousness vs fastidious

fastidiousness is a noun but fastidious is not a noun.

Word	Noun	Adjective	Verb	Adverb
fastidiousness	Yes	No	No	No
fastidious	No	Yes	No	No

fastidiousness (noun)	fastidious (noun)
the trait of being meticulous about matters of taste or style

fastidiousness (adjective)	fastidious (adjective)
	giving careful attention to detail; hard to please; excessively concerned with cleanliness
	having complicated nutritional requirements; especially growing only in special artificial cultures