# addition

Pronunciation: say "uh-DISH-uhn" /əˈdɪʃ.ən/

## Noun

1. Anything that is added to an existing thing, group, or whole.
   - Simple: Something new or extra that is put with what was already there.
   - _The glass conservatory is a recent addition to the Victorian house._
   - _Her latest addition to the collection was a rare first edition._
2. The act or process of adding one thing to another.
   - Simple: The act of putting one thing together with another.
   - _The recipe calls for the slow addition of the oil while you whisk._
   - _The museum announced the addition of three new galleries to its east wing._
3. The arithmetic operation of combining two or more numbers to produce their sum.
   - Simple: The kind of math where you put numbers together to find their total.
   - _Basic addition is taught alongside subtraction in the early grades._
   - _He checked the restaurant bill with some quick mental addition._
4. An organic chemical reaction in which two or more molecules combine to form a single larger molecule, called the adduct.
   - Simple: A kind of chemical change where two or more molecules join to make one bigger one.
   - _Bromine reacts with ethene by addition, yielding a single colorless product._
   - _The addition of hydrogen across the double bond turns the alkene into an alkane._

## Other meanings

- (noun) A dot placed to the right of a note indicating that its duration is to be lengthened by one half.
- (noun) In heraldry, something added to a coat of arms as a mark of honor.
- (noun) A title annexed to a person's name, as in legal documents, to identify the person more precisely.

## Origin

The sense of "what is added" dates from the 14th century. It came through Middle English addicioun and Old French adition, from Latin additiō, ultimately from addō ("add, put").

Source: DictionaryAI, https://dictionaryai.com/define/addition (written from Wiktionary data, CC BY-SA 4.0: https://creativecommons.org/licenses/by-sa/4.0/).