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

• annex
• extension
• penthouse

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, 2023 and 2024 featured a powerful El Niño, which tends to strengthen westerly winds in the Atlantic, making early development less likely. —Jim Foerster, Forbes.com, 2 June 2025

In addition to cost savings and a reduced carbon footprint, the Park District shares in expanding access to clean energy, improving grid resilience and creating jobs in the renewable energy industry, according to a May press release from E4. —Steve Sadin, Chicago Tribune, 2 June 2025

In addition, Hallmark Media named Jessica Tasler Noble chief culture officer, moving over from Hallmark Product & Retail, and succeeding Sabrina Wiewel, who will now serve as executive VP of Crayola Studios. —Alex Weprin, HollywoodReporter, 2 June 2025

In addition, Dean has announced a surprise underplay at London’s Shepherd’s Bush Empire on June 11 with tickets available to those who pre–order the album. —Thomas Smith, Billboard, 2 June 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)