stuffiness vs stuffy

stuffiness is a noun but stuffy is not a noun.

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

stuffiness (noun)	stuffy (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

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