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

Pot still is reference to the distilling apparatus, but also that mash bill of the addition of malted and un-malted barley into the mash bill. —Eric Blumer, CBS News, 11 Dec. 2025

In addition to embracing these colors, designers are incorporating tartan in unexpected ways, using it on rugs and lampshades as well as upholstery for modern furniture pieces. —Cornelia Powers, Vogue, 10 Dec. 2025

Chinese leaders in October announced development goals for the next five years would include greater efforts to boost consumption in addition to tech self-sufficiency. —Evelyn Cheng, CNBC, 10 Dec. 2025

The 6,758-guest vessel will combine popular elements of its predecessors – like MSC World America, which launched in 2025 – with new additions, according to Lynn Torrent, president of MSC Cruises North America. —Nathan Diller, USA Today, 10 Dec. 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)