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

But a third of the way into the season, the 27-year-old is proving to be Atlanta’s most important veteran addition of the offseason. —Josh Kendall, New York Times, 16 Oct. 2025

In addition to her three children, Ashley's also gotten closer to the two daughters Thomas shares with Alisa. —Emily Blackwood, PEOPLE, 15 Oct. 2025

In addition, as Gen Z’s influence grows, so does their impact on returns. —Lisa Lockwood, Footwear News, 15 Oct. 2025

Add eggs, one at a time, beating well after each addition. —Kathryn Gregory, Louisville Courier Journal, 15 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)