salary increase vs increase

salary increase and increase both are nouns.

Word	Noun	Adjective	Verb	Adverb
salary increase	Yes	No	No	No
increase	Yes	No	Yes	No

As nouns, increase is a hypernym of salary increase; that is, increase is a word with a broader meaning than salary increase:

Other hypernyms of salary increase include increment.

salary increase (noun)	increase (noun)
the amount a salary is increased	the act of increasing something
	the amount by which something increases
	a change resulting in an increase
	a process of becoming larger or longer or more numerous or more important
	a quantity that is added

salary increase (verb)	increase (verb)
	become bigger or greater in amount
	make bigger or more