deadening vs uninteresting

deadening is a noun but uninteresting is not a noun.

Word	Noun	Adjective	Verb	Adverb
deadening	Yes	Yes	No	No
uninteresting	No	Yes	No	No

deadening (noun)	uninteresting (noun)
the act of making something futile and useless (as by routine)

deadening (adjective)	uninteresting (adjective)
so lacking in interest as to cause mental weariness	arousing no interest or attention or curiosity or excitement
	characteristic or suggestive of an institution especially in being uniform or dull or unimaginative