the process of uniting two or more numbers into one sum, represented by the symbol +.
3.
the result of adding.
4.
something added.
5.
a wing, room, etc., added to a building, or abutting land added to real estate already owned.
6.
Chemistry. a reaction in which two or more substances combine to form another compound.
—Idiom
7.
in addition to, as well as; besides: In addition to directing the play, she designed most of the scenery.
[Origin: 1350–1400; ME addicio(u)n < L additiōn- (s. of additiō), equiv. to addit(us), ptp. of addere to add(ad-ad-+ di- put + -tus ptp. suffix) + -iōn--ion]
—Synonyms 1. joining. 3, 4. increase, enlargement; increment; accession, 4. supplement; appendix. 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.
1366 "that which is added," from O.Fr., from L. additionem (nom. additio) "an adding to, addition," from additus, pp. of addere (see add). Meaning "action of adding" first attested c.1440. Phrase in addition to "also" is from 1902.
a component that is added to something to improve it; "the addition of a bathroom was a major improvement"; "the addition of cinnamon improved the flavor"
2.
the act of adding one thing to another; "the addition of flowers created a pleasing effect"; "the addition of a leap day every four years" [ant: deduction]
3.
a 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"
4.
something added to what you already have; "the librarian shelved the new accessions"; "he was a new addition to the staff" [syn: accession]
5.
a suburban area laid out in streets and lots for a future residential area
6.
the arithmetic operation of summing; calculating the sum of two or more numbers; "the summation of four and three gives seven"; "four plus three equals seven" [syn: summation]
Ad*di"tion\, n. [F. addition, L. additio, fr. addere to add.]1. The act of adding two or more things together; -- opposed to subtraction or diminution. "This endless addition or addibility of numbers." --Locke. 2. Anything added; increase; augmentation; as, a piazza is an addition to a building. 3. (Math.) That part of arithmetic which treats of adding numbers. 4. (Mus.) A dot at the right side of a note as an indication that its sound is to be lengthened one half. [R.] 5. (Law) A title annexed to a man's name, to identify him more precisely; as, John Doe, Esq.; Richard Roe, Gent.; Robert Dale, Mason; Thomas Way, of New York; a mark of distinction; a title. 6. (Her.) Something added to a coat of arms, as a mark of honor; -- opposed to abatement. Vector addition (Geom.), that kind of addition of two lines, or vectors, AB and BC, by which their sum is regarded as the line, or vector, AC. Syn: Increase; accession; augmentation; appendage; adjunct.
![[P]](http://cache.lexico.com/g/d/premium_mh.gif){kind=small}
Audio Help [uh-dish-uh
