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

see also in addition, in addition to

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

In addition to the Sierra population, there are about 20 Sierra Nevada red foxes living in the Cascade mountain range of Northern California. —Clara Harter, Los Angeles Times, 11 Feb. 2026

Ski mountaineering is the newest addition to the lineup and the first sport added to the Winter Olympics since 2002. —Julianna Duennes Russ, Austin American Statesman, 10 Feb. 2026

In addition, the governor’s office has sought for the Bears to implement measures to make games more affordable, the sources said. —Jeremy Gorner, Chicago Tribune, 10 Feb. 2026

In addition to Trump’s reluctance this term to fire high-level Cabinet officials, and his disinterest in addressing his past Epstein friendship, Lutnick is also a longtime friend of the president who has defended his tariff regime against intra-party criticism. —Shelby Talcott, semafor.com, 10 Feb. 2026

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)