stuffy vs stuffiness

stuffy is not a noun while stuffiness is a noun.

Word	Noun	Adjective	Verb	Adverb
stuffy	No	Yes	No	No
stuffiness	Yes	No	No	No

stuffy (noun)	stuffiness (noun)
	dull and pompous gravity
	the quality of being close and poorly ventilated
	state of obstruction or stoppage or air in the nose or throat

stuffy (adjective)	stuffiness (adjective)
excessively conventional and unimaginative and hence dull
affected with a sensation of stoppage or obstruction
lacking fresh air