# extension

Pronunciation: say "ik-STEN-shuhn" /ɪkˈstɛnʃən/

## Noun

1. The act of stretching something out or enlarging it in length, width, or time.
   - Simple: The act of making something longer, bigger, or last more time.
   - _The extension of the contract gave both sides more time to negotiate._
   - _Stretching promotes the extension of muscles beyond their resting length._
2. A written agreement by a creditor granting a debtor additional time to repay a debt.
   - Simple: A written promise from a lender that gives a borrower more time to pay back money.
   - _The creditor granted a three-month extension on the overdue invoice._
   - _Without an extension in writing, the debtor risked defaulting on the loan._
3. A part added onto a building beyond its original structure.
   - Simple: A new part added onto a building after it was first built.
   - _The old house gained a glass extension overlooking the garden._
   - _A building permit was required before the extension could be built._
4. A short numerical code that directs a call to a specific telephone within a larger network.
   - Simple: A short number that connects you to one phone in a larger office system.
   - _Please call the front desk and ask for extension 210._
   - _Each department has its own extension on the office phone system._
5. In computing, an add-on piece of software that a user can choose to install to give an application extra features.
   - Simple: A small add-on that gives a program extra features.
   - _A browser extension can translate web pages into your language automatically._
   - _Developers released an extension that adds dark mode to the editor._
6. Ellipsis of file extension. — Ellipsis of file extension.
   - Simple: Ellipsis of file extension. The part of a file name after the dot that shows its type.
   - _Files with a .zip extension are compressed to save space._
   - _The program refused to open a file with an unfamiliar extension._
7. An outgrowth or added part that increases what something is able to do.
   - Simple: A part that grows out from something and adds to what it can do.
   - _The robotic arm acts as an extension of the surgeon's own reach._
   - _Critics saw the new policy as an extension of earlier reforms._
8. Clipping of hair extension, nail extension, or eyelash extension. — Clipping of hair extension, nail extension, or eyelash extension.
   - Simple: Clipping of hair extension, or of nail or eyelash extension. Extra length added to hair, nails, or lashes.
   - _Her stylist matched the extension to her natural hair color._
   - _One eyelash extension came loose after a week._
9. A strength exercise in which an arm or leg is straightened while working against a weight or other resistance.
   - Simple: An exercise where you straighten an arm or leg while pushing against weight.
   - _The trainer programmed a knee extension to strengthen her quads._
   - _A slow, controlled extension reduces strain on the joint._
10. University programs aimed at the wider community, usually adults, who are not enrolled as full-time students.
   - Simple: College classes made for adults in the community who are not full-time students.
   - _She earned a certificate through the university's extension without ever enrolling full time._
   - _The extension runs weekend workshops aimed at working professionals._
11. The condition or state of being extended in space or time.
   - Simple: The condition of being stretched out or spread over space or time.
   - _At full extension, the telescope brought distant stars into focus._
   - _After the injury, his knee would not reach full extension, so he walked with a slight limp._
12. The stretching of a broken bone along its length so its fragments are drawn back into a single straight line.
   - Simple: The pulling of a broken bone to bring its pieces back into a straight line.
   - _Before applying the cast, the surgeon performed extension to align the shattered fragments._
   - _Traction provides continuous extension that keeps the bone fragments straight while they heal._
13. The property of a body whereby it occupies a portion of space, and by analogy a stretch of time.
   - Simple: The way an object takes up room in space.
   - _For Descartes, extension is the defining property of physical substance._
   - _Two solid objects cannot share the same extension in space at the same moment._
14. In fencing, a simple offensive action in which the weapon arm is straightened forward toward the opponent.
   - Simple: In fencing, the move of straightening the sword arm forward toward your opponent.
   - _The coach drilled the extension until each fencer could threaten without committing fully._
   - _He scored by following his extension with a swift lunge._
15. The range of objects that a concept or general term applies to: its breadth of reference, the correlative of intension.
   - Simple: The number of things that a word or idea can cover.
   - _The term 'mammal' has a broader extension than 'dog,' which it includes._
   - _Logicians distinguish a term's extension from its intension, or defining content._
16. A widening of a word's meaning, so that it comes to refer to more than it originally did.
   - Simple: When a word grows to mean more things than it used to.
   - _The shift of 'cool' from a temperature word to a term of approval is a clear case of extension._
   - _Linguists describe how extension gradually loosens the original limits of a word's meaning._
17. In logic, the set of argument tuples that satisfy a given predicate: the things of which it is true.
   - Simple: In logic, the collection of things for which a rule comes out true.
   - _The extension of the predicate 'is red' contains every red object._
   - _Two predicates with the same extension are coextensive, even when they differ in meaning._
18. In group theory, a short exact sequence 1→H→E→G→1, or the middle group E that contains H as a normal subgroup with quotient G.
   - Simple: In math, a larger group built by fitting one group inside another in a set way.
   - _An extension of G by H places H as a normal subgroup of E whose quotient is G._
   - _Central extensions, where H lies in the center of E, arise throughout the theory of projective representations._
19. In homological algebra, a short exact sequence 0→B→E→A→0, or the middle object E that contains B as a subobject with quotient A.
   - Simple: In math, a structure that links two objects, with one of them sitting inside it.
   - _An extension of A by B fits B inside E so that the quotient is A._
   - _Extensions of one module by another are classified by the Ext functor._
20. In ring theory, the ideal in the target ring generated by the image of a given ideal under a ring homomorphism.
   - Simple: In math, the new ideal formed when an ideal is carried over by a map between rings.
   - _The extension of a prime ideal need not remain prime in the larger ring._
   - _Computing the extension of an ideal along an inclusion is a routine step in localization._
21. In Bantu languages, a derivational morpheme suffixed to a verb root that alters its meaning or the arguments it takes.
   - Simple: In some African languages, a small part added to a verb to change its meaning.
   - _The applicative extension adds a beneficiary argument to the verb._
   - _Swahili stacks several extensions onto a single verb root._

## Origin

It comes from Middle English "extensioun", from Old French "estension", which in turn derives from Latin "extensiō, extensiōnem".

Source: DictionaryAI, https://dictionaryai.com/define/extension (written from Wiktionary data, CC BY-SA 4.0: https://creativecommons.org/licenses/by-sa/4.0/).