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 higher construction costs, the convention center expansion is hamstrung by the city’s lack of control over a key waterfront parcel that would be needed to complete the project. —Lori Weisberg, San Diego Union-Tribune, 25 Feb. 2026

In addition to his daughter, survivors include his sons, Christopher and Timothy, and his grandson, Brandon. —Mike Barnes, HollywoodReporter, 24 Feb. 2026

Italy is home to six of the more than 75 brands within the LVMH portfolio, including Bulgari, Acqua di Parma, Pucci and Cova, in addition to Loro Piana and Fendi. —Martino Carrera, Footwear News, 24 Feb. 2026

The offensive line is in transition once again, with five new additions who were starters a year ago. —Manny Navarro, New York Times, 24 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)