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

How Tielemans overcame early toils is often used as a source of encouragement by new additions who seem peripheral at first. —Jacob Tanswell, New York Times, 23 Oct. 2025

In addition, there are numerous special award winners in 2025, including leadership awards given to Trent Hunt with Shepherd Insurance, Bob Koetter with The Koetter Group, and Christen Byrne with Bluegrass Center for Autism. —Kathryn Gregory, Louisville Courier Journal, 23 Oct. 2025

In addition, pests like those obnoxious mosquitoes will have longer active seasons prior to the beginning of the first freeze. —Janet Loehrke, USA Today, 22 Oct. 2025

In addition to gin, the company makes rye whiskey, bourbon and vermouth. —Jalen Williams, Freep.com, 22 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)