ex·ten·sion | \ik-ˈsten(t)-shən \

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

b : denotation sense 4

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

The School Board recently heard a presentation on a plan to restore several minutes students had with teachers in the past that was an extension of their lunch period. Linda Girardi, Aurora Beacon-News, "West Aurora may try new lunch period model for sixth-graders," 10 July 2018 Part of that vision is the extension of the Ronald Reagan Parkway. Emily Hopkins, Indianapolis Star, "In Hendricks County, Ronald Reagan Parkway extension pits science against growth," 9 July 2018 McCarthy, the classmate’s lawyer, said Ramos was adept at using the legal system to suggest a sense of legitimacy to what was really an extension of his stalker-like behavior. Anchorage Daily News, "Maryland newspaper shooting suspect’s anger flared, and fell silent. Then it exploded, police say," 8 July 2018 The service is an extension of Amazon Key, which the company debuted in November for delivery people to enter customer homes without keys. Jerry Reynolds, Houston Chronicle, "Understand what a ‘spot delivery’ is," 7 July 2018 Steven Tompkins, the Suffolk County sheriff, said Tuesday’s debate was an extension of his efforts to engage the inmates in civic discourse. New York Times, "Inmates Question Prospective Prosecutors in Jailhouse Campaign Debate," 26 June 2018 The stilts create a stable base for the small studio, which is an extension of the owners’ primary residence. Liz Stinson, Curbed, "Solar-powered modern studio appears to float in midair," 25 June 2018 Thompson is under contract through the 2019 season, but is currently eligible for a four-year extension (in addition to the remaining year on his current deal). Ben Ladner, SI.com, "Golden State Warriors Off-Season Preview: Kevin Durant Appears to Be a Safe Bet to Resign," 10 June 2018 The development group has asked for an extension of city entitlements first granted to the project in 2007 and extended last year. Ryan Lillis And Tony Bizjak, sacbee, "Is a planned 40-story tower in downtown Sacramento finally on track?," 12 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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Phrases Related to extension

extension lead

Statistics for extension

Last Updated

8 Oct 2018

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


ex·ten·sion | \ik-ˈsten-shən \

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 \

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



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

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not any or not one

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