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[uh-dish-uh n] /əˈdɪʃ ən/
the act or process of adding or uniting.
the process of uniting two or more numbers into one sum, represented by the symbol +.
the result of adding.
something added.
a wing, room, etc., added to a building, or abutting land added to real estate already owned.
Chemistry. a reaction in which two or more substances combine to form another compound.
in addition to, as well as; besides:
In addition to directing the play, she designed most of the scenery.
Origin of addition
1350-1400; Middle English addicio(u)n < Latin additiōn- (stem of additiō), equivalent to addit(us), past participle of addere to add (ad- ad- + di- put + -tus past participle suffix) + -iōn- -ion
Related forms
preaddition, noun
readdition, noun
Can be confused
addition, edition.
1. joining. 3, 4. increase, enlargement; increment; accession, 4. supplement; appendix.
Synonym Study
4.Addition, accessory, adjunct, attachment mean something joined onto or used with something else. Addition is the general word, carrying no implication of size, importance, or kind, but merely that of being joined to something previously existing: an addition to an income, to a building, to one's cares. An accessory is a subordinate addition to a more important thing, for the purpose of aiding, completing, ornamenting, etc.: accessories to a costume. An adjunct is a subordinate addition that aids or assists a main thing or person but is often separate: a second machine as an adjunct to the first. An attachment is an accessory part that may be easily connected and removed: a sewing machine attachment for pleating. Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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Examples from the Web for addition
Contemporary Examples
Historical Examples
  • I have another favour to ask, in addition to the many claims you already have upon me.

    Philothea Lydia Maria Child
  • But the family-party was soon to be broken up—not by subtraction, but by addition.

    Weighed and Wanting George MacDonald
  • In addition, there were as many of books and magazines as she could wish.

    Within the Law Marvin Dana
  • In addition, these vegetables may be combined in almost any way.

    Woman's Institute Library of Cookery, Vol. 4 Woman's Institute of Domestic Arts and Sciences
  • The same singers, with the addition of Anastasia Robinson, appeared in the season of 1721-22.

    Handel Edward J. Dent
British Dictionary definitions for addition


the act, process, or result of adding
a person or thing that is added or acquired
a mathematical operation in which the sum of two numbers or quantities is calculated. Usually indicated by the symbol +
(mainly US & Canadian) a part added to a building or piece of land; annexe
(obsolete) a title following a person's name
(adverb) in addition, also; as well; besides
(preposition) in addition to, besides; as well as
Word Origin
C15: from Latin additiōn-, from addere to add
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for addition

late 14c., "action of adding numbers;" c.1400, "that which is added," from Old French adition "increase, augmentation" (13c.), from Latin additionem (nominative additio) "an adding to, addition," noun of action from past participle stem of addere (see add). Phrase in addition to "also" is from 1681.

Online Etymology Dictionary, © 2010 Douglas Harper
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addition in Science
The act, process, or operation of adding two or more numbers to compute their sum.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Idioms and Phrases with addition


The American Heritage® Idioms Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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