pretentious vs pretentiousness

pretentious is not a noun while pretentiousness is a noun.

Word	Noun	Adjective	Verb	Adverb
pretentious	No	Yes	No	No
pretentiousness	Yes	No	No	No

pretentious (noun)	pretentiousness (noun)
	the quality of being pretentious (behaving or speaking in such a manner as to create a false appearance of great importance or worth)
	lack of elegance as a consequence of being pompous and puffed up with vanity

pretentious (adjective)	pretentiousness (adjective)
making claim to or creating an appearance of (often undeserved) importance or distinction
intended to attract notice and impress others
(of a display) tawdry or vulgar