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.
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.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2019 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.