mitigate vs decrease

mitigate is not a noun while decrease is a noun.

Word	Noun	Adjective	Verb	Adverb
mitigate	No	No	Yes	No
decrease	Yes	No	Yes	No

As verbs, decrease is a hypernym of mitigate; that is, decrease is a word with a broader meaning than mitigate:

Other hypernyms of mitigate include lessen, minify.

mitigate (noun)	decrease (noun)
	the act of decreasing or reducing something
	the amount by which something decreases
	a change downward
	a process of becoming smaller or shorter

mitigate (verb)	decrease (verb)
to temper	decrease in size, extent, or range
lessen or to try to lessen the seriousness or extent of	make become smaller