Nouns

(n)addition, increase, gaina quantity that is added“there was an addition to property taxes this year”, “they recorded the cattle's gain in weight over a period of weeks”
(n)increasea change resulting in an increase“the increase is scheduled for next month”
(n)increase, increment, growtha process of becoming larger or longer or more numerous or more important“the increase in unemployment”, “the growth of population”
(n)increase, incrementthe amount by which something increases“they proposed an increase of 15 percent in the fare”
(n)increase, step-upthe act of increasing something“he gave me an increase in salary”

Verbs

(v)increasebecome bigger or greater in amount“The amount of work increased”
(v)increasemake bigger or more“The boss finally increased her salary”, “The university increased the number of students it admitted”