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

Under Ohio law, the country club is owed triple damages for the theft in addition to punitive and other damages, making the total for both Lee and Sulky nearly $4 million. —Kevin Grasha, The Enquirer, 26 Aug. 2025

Below are the five core phases, in addition to construction and operations. —Yuvraj Kshirsagar, Forbes.com, 25 Aug. 2025

In addition to the usual channel rotation, this season’s streaming rights extend to Amazon Prime, Netflix, Peacock and YouTube. —Steven Louis Goldstein, New York Times, 25 Aug. 2025

In addition to dealing with the wealthy guests’ problems, Daniel is also on the trail of Alice, one of the owner’s daughters who disappeared a month earlier. —Denise Petski, Deadline, 25 Aug. 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)