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Definition of extension

extension

/ɪkˈstɛn.ʃən/
ex · ten · sion

Plural:extensions
•
Adjective:extensional
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extension Lexical Profile

extension Game Scores & Validity

• noun

1

The act or process of making something longer, larger, or more widespread in space, scope, or time; an additional period of time granted beyond an original deadline.

Example

"The professor granted the student a two-week extension to finish the research paper."


2

A part that is added to something to enlarge or prolong it, especially an extra room or wing built onto an existing building, an electrical cord, or artificial hair.

Example

"They built a single-story extension at the back of the house to create a larger kitchen."


3

A subsidiary telephone on the same central line as the main telephone, or the specific code number assigned to an individual telephone within an organization's internal network.

Example

"Please dial the main office number and ask the receptionist for extension 402."


4

In computing, a small software module that adds specific features to a larger program (such as a web browser), or a suffix at the end of a filename indicating its file format.

Example

"She installed an ad-blocking extension on her web browser and saved the document with a .pdf extension."


5

In anatomy and physiology, a movement that increases the angle between the bones of a limb at a joint, resulting in the straightening of the limb or body part.

Example

"The physical therapist measured the patient's range of knee extension after the surgery."

Synonyms
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Antonyms
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• Rhymes for extension

Word Origin & Etymology

Borrowed in Middle English via Old French from the Late Latin 'extensio' ('a stretching out'), a noun of action from 'extendere' ('to stretch out'), formed from 'ex-' ('out') and 'tendere' ('to stretch').

Cite this Entry


Wordmom. (2026). Definition of Extension. In Wordmom Dictionary. Retrieved Nov 5, 2026, from https://wordmom.com/dictionary/extension
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