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

The sweeps, in addition to crowd-management responsibilities, are typically dealt with by local police, who often have more experience and training in de-escalating large demonstrations and tamping down civil unrest. —Anna Schecter, CBS News, 28 Jan. 2026

As such, the front office could be choosing between retaining Simons and using the full nontaxpayer midlevel exception for a new addition. —Danny Leroux, New York Times, 28 Jan. 2026

In addition to where in the stadium tickets can purchased, Razorback Foundation donor levels and priority points also dictate how parking passes around the stadium are distributed and how many tickets are available for purchase in certain sections. —Matt Jones, Arkansas Online, 28 Jan. 2026

Viewed as a run-first offense, the addition of Concepcion, along with Mario Craver, changed that. —Tony Catalina, Austin American Statesman, 27 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)