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 Expedia, many other organizations offer heritage travel, often with expert guides. —Michael Goldstein, Forbes.com, 21 Jan. 2026

In addition to stars Evan Peters, Ashton Kutcher, Rebecca Hall, Anthony Ramos and Jeremy Pope, The Beauty features a roster of celebrity guest appearances. —Emily Blackwood, PEOPLE, 21 Jan. 2026

Armani Beauty Luminous Silk Natural Glow Blurring Foundation A reformulation of your favorite beauty product is always a bit alarming, but Armani’s new addition is more like a glow up. —Reece Andavolgyi, InStyle, 21 Jan. 2026

In medium- or lower-light rooms, however, sun-loving plants like succulents, cacti, and bird of paradise will benefit from the addition of a grow light. —Alexandra Jones, The Spruce, 21 Jan. 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)