noun

addition

uh-DIH-shuhn/əˈdɪʃn/

The joining of something to an existing amount or whole.

The fresh addition gives the older house another room.

A newly built small room attached to the side of an older, larger house: the fresh wing is visibly an addition to the existing whole.

Etymology

From a verb meaning “join” or “attach,” addition named the act of adding. It also came to name the result: the thing joined to an existing whole or group.

In context

Professor Stevenson12:09

get a larger facility like put an addition on your building

Law & Marginal Effects: Understanding Diminishing Returns in Law | Law & Economics Seminar

More examples

The puppy is a welcome addition to our family.
The children practice addition with small wooden blocks.
In addition to lunch, the ticket includes a guided tour.

Forms

addition · additions

add verb — To join something to an existing whole.

additional adjective — Extra or added to what already exists.

Similar words

increase: Focuses on growth in amount rather than something being joined.
extension: Often enlarges an existing structure, period, or scope.