-io

an action, process, or result

Forms

-io
-ion- — The longer form used before Latin endings.
-ion — The form carried into many English nouns.

Origin

An old Latin noun ending, inherited from earlier Indo-European word formation.

Note

The ending can name both an activity and what that activity produces.

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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

additLatinadd to, join, attach

+ionLatinan action, process, or result

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.