increase increase (ĭn-krēsʹ) verbincreased, increasing, increasesverb, intransitive1. To become greater or larger. 2. To multiply; reproduce. verb, transitiveTo make greater or larger. noun(ĭnʹkrēs)Abbr. inc., incr.1. The act of increasing: a steady increase in temperature. 2. The amount or rate by which something is increased: a tax increase of 15 percent. 3. Obsolete. Reproduction and spread; propagation. idiom.on the increaseIncreasing, especially in frequency of occurrence: Crime is on the increase. increasʹable adjective increasʹer noun increasʹingly adverbSynonyms: increase, expand, enlarge, extend, augment, multiply. These verbs mean to make or become greater or larger. Increase applies most widely; it sometimes suggests steady growth: “Absence diminishes mediocre passions and increases great ones” (La Rochefoucauld). The mayor”s political influence rapidly increased. To expand is to increase in size, area, volume, bulk, or range: He does exercises to expand his chest. “Work expands so as to fill the time available for its completion” (C. Northcote Parkinson). Enlarge refers to expansion in size, extent, capacity, or scope: The landowner enlarged her property by repeated purchases. Our group of friends is enlarging by leaps and bounds. To extend is to lengthen in space or time or to broaden in range, as of application: The transit authority extended the subway line to the next town. The baseball season may be extended. “Hiseye, like his mind, sought an extended view” (Dumas Malone). Augment usually applies to what is already developed or well under way: augmented her collection of books; depression that augments with each visit to the hospital. To multiply is to increase in number, especially by propagation or procreation: “As for my cats, they multiplied” (Daniel Defoe). “May thy days be multiplied!” (Sir Walter Scott).