n. Idioms: 1. Mathematics a. The operation that, for positive integers, consists of increasing by a definite number of increments of 1. The operation is extended to other numbers according to the additive properties of positive integers and other algebraic properties. b. Any of certain analogous operations involving mathematical objects other than numbers. 2. The process of adding or joining something to something else, typically to make it larger: The addition of a porch to the house would increase its resale value. 3. Something added: This painting would make a fine addition to the museum's collection. in addition Also; as well. in addition to Over and above; besides. [Middle English, from Old French, from Latin additiō, additiōn-, from additus, past participle of addere, to add; see ADD.] ad·dition·al adj. ad·dition·al·ly adv. |
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2022 by HarperCollins Publishers. All rights reserved.