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

Phrases

in addition

: besides entry 2, also

The job requires a college degree and, in addition, at least two years of experience.

in addition to

: combined or associated with : besides entry 1 sense 2

In addition to soup, several salads were served.

Synonyms

• 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 yards of open grassy areas for Pickles and Franklin to roam freely, there is a pool, sauna, pickleball court, outdoor kitchen, and lots of shaded or umbrella-covered seating. —Lennie Omalza, Louisville Courier Journal, 2 Oct. 2025

The squad has a deeper bench this season thanks to the additions of guards Jordan Clarkson and Malcolm Brogdon and big man Guerschon Yabusele. —Robert Marvi, MSNBC Newsweek, 1 Oct. 2025

Sharkey, meanwhile, offered a list of shoe recommendations featuring styles by Sorel, Merrell and Columbia, in addition to a couple of other names. —Jaden Thompson, Footwear News, 1 Oct. 2025

In addition to starring, Brosnahan executive produces. —Nellie Andreeva, Deadline, 1 Oct. 2025

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

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)