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

The beverage program will offer an extensive selection of Old World wines with an emphasis on Italian Barolo vintages in addition to an exciting cocktail menu. —Amber Love Bond, Forbes.com, 8 July 2025

In addition, Hynes is due to perform as part of Pitchfork Music Festival Paris on Monday, November 3. —Matthew Strauss, Pitchfork, 8 July 2025

In addition, at age 28, Duran is older than any of the Boston outfielders except for the 34-year-old Refsnyder. —Jon Vankin, MSNBC Newsweek, 8 July 2025

However, as is the case with most federal laws — especially one that’s nearly 900 pages long and peppered with plenty of eleventh-hour additions — the outcomes aren’t always that cut and dry. —Alicia Wallace, CNN Money, 8 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)