fastidious vs fastidiousness

fastidious is not a noun while fastidiousness is a noun.

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

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

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