abbreviate vs decrease

abbreviate is not a noun while decrease is a noun.

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

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

Other hypernyms of abbreviate include lessen, minify.

abbreviate (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

abbreviate (verb)	decrease (verb)
shorten	decrease in size, extent, or range
reduce in scope while retaining essential elements	make become smaller