ex·​ten·​sion | \ ik-ˈsten(t)-shən How to pronounce extension (audio) \

Definition of extension

1a : the action of extending : state of being extended
b : an enlargement in scope or operation tools are extensions of human hands
2a : the total range over which something extends : compass
3a : the stretching of a fractured or dislocated limb so as to restore it to its natural position
b : an unbending movement around a joint in a limb (such as the knee or elbow) that increases the angle between the bones of the limb at the joint — compare flexion sense 4a
4 : a property whereby something occupies space
5 : an increase in length of time specifically : an increase in time allowed under agreement or concession
6 : a program that geographically extends the educational resources of an institution by special arrangements (such as correspondence courses) to persons otherwise unable to take advantage of such resources
7a : a part constituting an addition
b : a section or line segment forming an additional length
c : an extra telephone connected to the principal line
d : a length of natural or synthetic hair that is worn attached to one's natural hair
e : a series of usually three or four characters following a dot at the end of the name of a computer file that specifies the file's format or purpose
8 : a mathematical set (such as a field or group) that includes a given and similar set as a subset

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Examples of extension in a Sentence

extension of the patient's life He's asking for a contract extension. Make sure that the muscles get the proper amount of extension. I missed the deadline but was granted an extension.
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Recent Examples on the Web

While the Wild would love to have an extension ironed out before the start of next season, Spurgeon could choose to bet on himself, play out his current contract, and test free agency next offseason. Dane Mizutani, Twin Cities, "Wild GM Paul Fenton wants to re-sign, not trade, star defenseman Jared Spurgeon," 14 June 2019 In March backbenchers even took control of the agenda to call for an extension. The Economist, "Tory candidates are misleading people about a no-deal Brexit," 13 June 2019 Ilkay Gundogan's contract with Manchester City is set to expire in 2020 and the Citizens are yet to confirm whether the midfielder will be awarded with an extension to his current deal. SI.com, "Transfer Rumours: Rodriguez Wanted by Napoli, Arsenal Eye Up Dakonam, Gundogan to Dortmund & More," 12 June 2019 The sleek new streetcars have notched more than five million free rides in their first two and a half years, and an extension to the 2.2-mile starter line is already in the works. National Geographic, "How pigeons landed in cities, and more breakthroughs," 12 June 2019 Hairstylist Renato Campora is responsible for adding hair extensions for the show and shared some behind-the-scenes photos to his Instagram. Elizabeth Denton, Allure, "Priyanka Chopra’s Waist-Length Extensions Are Giving Me Life," 2 May 2019 In the video, Ariana is sporting various wings and hair extensions. Tamara Fuentes, Seventeen, "All the Hidden Meanings in Ariana Grande's "7 Rings" Lyrics," 18 Jan. 2019 The dresses are made out of real human hair extensions, and are inspired by artist Rebecca Horn’s performances and designer Martin Margiela. Lane Florsheim, WSJ, "The Costume Designer From ‘Suspiria’ Shows Off Her 5 Most Dramatic Looks," 26 Oct. 2018 Jenner, a nymph born when Zeus threw a track of hair extensions into a boiling ocean, is part of the inescapable and unavoidable Kardashian clan that has dominated television and pop culture for the last decade. Alex Abad-santos, Vox, "The controversy over “Kylie Jenner, self-made billionaire,” explained," 13 July 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'extension.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of extension

15th century, in the meaning defined at sense 1a

History and Etymology for extension

Middle English, from Late Latin extension-, extensio, from Latin extendere

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Statistics for extension

Last Updated

18 Jun 2019

Look-up Popularity

Time Traveler for extension

The first known use of extension was in the 15th century

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More Definitions for extension



English Language Learners Definition of extension

: the act of making something longer or greater
: the act of straightening or stretching something (such as an arm or a leg)
: extra time allowed for doing something


ex·​ten·​sion | \ ik-ˈsten-shən How to pronounce extension (audio) \

Kids Definition of extension

1 : the act of making something longer or greater extension of the sail
2 : an increase in length or time
3 : a part forming an addition or enlargement


ex·​ten·​sion | \ ik-ˈsten-chən How to pronounce extension (audio) \

Medical Definition of extension

1 : the stretching of a fractured or dislocated limb so as to restore it to its natural position
2 : an unbending movement around a joint in a limb (as the knee or elbow) that increases the angle between the bones of the limb at the joint — compare flexion sense 1

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Legal Definition of extension

: an increase in length of time specifically : an increase in the time allowed under an agreement

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Comments on extension

What made you want to look up extension? Please tell us where you read or heard it (including the quote, if possible).


incapable of being surmounted or overcome

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