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

Phrases

in addition

: besides entry 2, also

The job requires a college degree and, in addition, at least two years of experience.

in addition to

: combined or associated with : besides entry 1 sense 2

In addition to soup, several salads were served.

Synonyms

• annex
• extension
• penthouse

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

Auckland City earned $3.58m USD for their participation in the tournament, in addition to a $1m bonus from FIFA for the draw against Boca. —Adam Crafton, New York Times, 27 June 2025

In addition to the traditional People’s Choice audience awards handed out by TIFF (including the most popular overall movie in the festival’s lineup being considered an instant awards season contender), Toronto this year will also hand out a first-ever International People’s Choice Award. —Etan Vlessing, HollywoodReporter, 26 June 2025

The Beach Boys Climb Multiple Billboard Charts The same gathering of the Beach Boys’ most familiar tunes appears on two other Billboard lists, in addition to the Billboard 200 and the Top Streaming Albums roster. —Hugh McIntyre, Forbes.com, 26 June 2025

In addition to the images, NASA researchers compiled the galaxy datasets into a sonification by separating out each wavelength, rotating them, and stacking them on top of one another in order of their frequency. —Andrew Paul, Popular Science, 26 June 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)