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

Moss is also executive producing under her Love & Squalor Pictures banner in addition to starring. —Joe Otterson, Variety, 12 June 2026

In addition to serving as a broadcaster, Phillips has written regularly for the UK’s biggest newspapers, The Times, The Daily Mail, The Sun and The Sunday Times. —Denise Petski, Deadline, 12 June 2026

Then Artistic Milliners made a cut-and-sew move with the addition of a garment factory in Parras, Mexico, which now operates as Artistic Milliners Mexico. —Sj Studio, Footwear News, 12 June 2026

In addition to demonstrating ROI, another key aspect of navigating changing pricing models will be having the ability to flexibly switch suppliers. —Martin Taylor, Forbes.com, 12 June 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)