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 the spread, total and moneyline markets, a bet on the method of victory or number of rounds will also qualify for this promo. —Tyler Everett, MSNBC Newsweek, 20 July 2025

In addition to the elevated dining, first class passengers on Acela are also treated to other perks, like access to station lounges, including the Metropolitan Lounge at New York's Moynihan Train Hall, which features large glass windows, contemporary flooring, Wi-Fi, and snacks. —Michael Cappetta, Travel + Leisure, 20 July 2025

That means Superman only has a few days left to itself before facing direct competition, in addition to losing Imax screens and other premium-large format auditoriums to Fantastic Four, which is tracking to open to $100 million to $110 million domestically. —Pamela McClintock, HollywoodReporter, 20 July 2025

Enterprise's data suggests Americans — in addition to saving money and avoiding air travel — are interested in culinary and cultural escapes. —Christopher Elliott, Forbes.com, 20 July 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)