addition

noun

ad·​di·​tion ə-ˈdi-shən 

a-

1

: a part added (as to a building or residential section)

The addition expanded the kitchen.

2

: anything or anyone added : increase

The clerk was a recent addition to the staff.

3

: the act or process of adding

a recipe enhanced by the addition of freshly ground pepper

especially : the operation of combining numbers so as to obtain an equivalent simple quantity

schoolchildren learning about addition and subtraction

4

: direct chemical combination of substances into a single product

see also:

in addition in addition to

Synonyms of addition

• extension
• annex

Examples of addition in a Sentence

The children learned addition and subtraction.

The museum's collection includes several new additions.

Recent Examples on the Web

In addition to a requirement for a warrant to access Americans' data, critics also want greater protections on how the FBI or other agencies can search communications and how that is reported to the public. —ABC News, 15 Apr. 2026

In the aftermath of the Google fiasco, Cukor turns to Palantir (in addition to Microsoft and Amazon) to make Maven a reality. —Gideon Lewis-Kraus, New Yorker, 15 Apr. 2026

In addition, Ware continued to display a feathery 3-point stroke, with a pair in the first half. —Ira Winderman, Sun Sentinel, 15 Apr. 2026

Other new additions to the cast in the follow-up to the iconic witchy romance are Joey King as Sally's daughter, along with Maisie Williams, Xolo Maridueña and Solly McLeod. —Madison E. Goldberg, PEOPLE, 15 Apr. 2026

Word History

Etymology

Middle English addicioun, borrowed from Anglo-French addicion, borrowed from Latin additiōn-, additiō, from addi-, variant stem of addere "to add" + -tiōn-, -tiō, suffix of action nouns

First Known Use

14th century, in the meaning defined at sense 1

Phrases Containing addition

• in addition
• in addition to

Rhymes for addition

• admission
• ambition
• attrition
• audition
• clinician
• cognition
• coition
• commission
• condition
• contrition
• dentition
• dismission

Kids Definition

addition

noun

ad·​di·​tion ə-ˈdish-ən 

a-

1

: the result of adding : increase

2

: the act, process, or operation of adding

3

: a part added (as to a building)