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

In addition to her legal troubles, Aileen also suffered from mental health struggles and reportedly attempted suicide six times, from the ages of 14 to 22. —Caroline Blair, PEOPLE, 30 Oct. 2025

In addition to the studio mandate to crush the competition, Browning had an additional motivation to focus his film on sideshow. —JSTOR Daily, 30 Oct. 2025

In addition to her daughter, survivors include her son, Jake; son-in-law Wayne; and grandchildren Eli and Chaya. —Mike Barnes, HollywoodReporter, 29 Oct. 2025

These sandals are just the latest addition to Harvey’s ever-evolving flip-flop collection. —Kelsey Stewart, Footwear News, 29 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)