extension
ik-STEN-shun
Extension (noun) means an extra part added to something to make it larger or longer, or an extra period of time granted beyond an original deadline. Example: “They built a single-storey extension at the back of the house.”
noun
1
An extra part added to something to make it larger or longer, or an extra period of time granted beyond an original deadline.
"They built a single-storey extension at the back of the house."
"I asked my tutor for a week's extension on the essay."
2
A small program that adds features to a web browser or other software.
"Install the extension and a save button appears in the toolbar."
"Some extensions can read everything you type, so check the permissions."
3
An additional telephone line within an office or building, or the short number that reaches it.
"Call the main switchboard and ask for extension 214."
"There's an extension in the kitchen."
How to use extension
Learner’s notesIn plain EnglishSomething added on to make a thing bigger, longer or more useful.
Memory tip
You 'grant' or 'request' an extension of time, and you 'install' a software extension.
Trace the full origin ↓
Easily confused with
Common pairings
build an extension
request an extension
browser extension
extension number
hair extensions
Vocabulary Flow
Build your vocabulary from words like extension.
Vocabulary Flow serves the next word, and the next — meaning, pronunciation and an example each time. Practice at your level, or learn English in your own language.
Start vocabulary practice
Fill the gap
Can you complete this real example?
They built a single-storey _____ at the back of the house.
Etymology
From Latin extensio, from extendere ('to stretch out'), from ex ('out') plus tendere ('to stretch').
Synonyms
View more →
addition
annexe
enlargement
prolongation
postponement
add-on
plug-in
module
elongation
propagation
annex
wing
Antonyms
flexion
Related words
Rhymes for extension
region
billion
ablation
allusion
emulsion
ideation
novation
abortion
abrasion
diffusion
elocution
oxidation
See all rhymes for extension →
Frequently asked questions
What is the difference between an extension and a plug-in?
In browsers the terms now overlap heavily. Historically a plug-in was separate software that let the browser handle a media type it could not read on its own, while an extension is written for the browser itself to add features to the interface. Modern browsers have retired plug-ins and use 'extension' for almost everything.
What is a file extension?
It is the suffix after the final dot in a filename, such as .pdf or .jpg, which tells the operating system what kind of file it is and which program should open it. Changing it does not convert the file; it only changes what the system expects.
How do you ask for a deadline extension?
Ask early, before the deadline passes, state plainly why you need it, and propose a specific new date rather than an open-ended delay. Confirming it in writing protects both sides.
What is the meaning of extension?
"extension" (noun) means an extra part added to something to make it larger or longer, or an extra period of time granted beyond an original deadline.
