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 of addition

• 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

Both are solid additions to a terrible defense, but there’s still work to do in the secondary. —Eddie Brown, San Diego Union-Tribune, 4 Dec. 2025

In addition to a homemade hot breakfast and cozy bedding, guests have access to a whole host of amenities. —Tara Massouleh McCay, Southern Living, 3 Dec. 2025

In addition to Cantwell, Miami’s offensive lineman signees are four-star tackle Ben Congdon, four-star interior offensive lineman Joel Ervin, three-star interior lineman Canon Pickett, three-star tackle Rhys Woodrow, and three-star interior lineman JJ Sparks. —Jordan McPherson, Miami Herald, 3 Dec. 2025

One of the most exciting additions for Henges is the addition of shelter beds for women this year. —Kansas City Star, 3 Dec. 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)