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

For a more casual vibe, visit one of downtown’s newer additions, Alma Mexico Restaurant & Bar. — Tara Massouleh McCay, Southern Living, 27 Sep. 2026

Tiny Tiger Stripe pumpkins would make an adorable addition to your Halloween tablescape or fall mantel. — Sophia Beams, Better Homes & Gardens, 27 Sep. 2026

Consensus is for 58,000 private-sector jobs additions, according to FactSet. — Zev Fima,kevin Stankiewicz, CNBC, 27 Sep. 2026

If the Marlins can avoid another late-season collapse, get more consistency from their young core, stay healthy and make the right additions when necessary, 2027 can look very different for McCullough’s group. — Brandon Liguori, Miami Herald, 27 Sep. 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)