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

The Rockets traded for Durant in the offseason, but didn’t really get to see what that addition did for the team in a postseason setting. —Dan Santaromita, New York Times, 2 May 2026

In addition to its stake in the maker of automatic timepiece movements Kenissi and its own watchmaking manufacture, the French house is investing in independents. —Lily Templeton, Footwear News, 1 May 2026

In addition the show's regular season, Rutter has competed in multiple follow-up specials, including the Tournament of Champions, the Battle of the Decades, the Ultimate Tournament of Champions and 2020's Greatest of All Time Tournament. —Christopher Rudolph, PEOPLE, 1 May 2026

In addition to stalking and domestic violence crimes, the companies must also act in cases that involve violations of protective orders in stalking cases. —Tim Stelloh, NBC news, 1 May 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

Phrases Containing addition

• in addition
• in addition to

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)