of or relating to extension courses.

Origin of extension

1350–1400; Middle English < Latin extēnsiōn- (stem of extēnsiō). See extensive, -ion
Related formsex·ten·sion·al·i·ty, ex·ten·sion·al·ism, nounex·ten·sion·al, adjectiveex·ten·sion·al·ly, adverbex·ten·sion·less, adjectivenon·ex·ten·sion, nounnon·ex·ten·sion·al, adjectivepro·ex·ten·sion, adjectivesu·per·ex·ten·sion, noun

Synonyms for extension

1. stretching, expansion, enlargement, increase, dilation. 3. lengthening, protraction, continuation. 4. delay. 6. limit.

Antonyms for extension

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for extension

Contemporary Examples of extension

Historical Examples of extension

British Dictionary definitions for extension



the act of extending or the condition of being extended
something that can be extended or that extends another object
the length, range, etc, over which something is extended; extent
an additional telephone set connected to the same telephone line as another set or other sets
a room or rooms added to an existing building
a delay, esp one agreed by all parties, in the date originally set for payment of a debt or completion of a contract
the property of matter by which it occupies space; size
  1. the act of straightening or extending an arm or leg
  2. its position after being straightened or extended
med a steady pull applied to a fractured or dislocated arm or leg to restore it to its normal positionSee also traction (def. 3)
  1. a service by which some of the facilities of an educational establishment, library, etc, are offered to outsiders
  2. (as modifier)a university extension course
  1. the class of entities to which a given word correctly applies: thus, the extension of satellite of Mars is the set containing only Deimos and PhobosCompare intension (def. 1a)
  2. conservative extensiona formal theory that includes among its theorems all the theorems of a given theory

Word Origin for extension

C14: from Late Latin extensiō a stretching out; see extend
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for extension

c.1400, from Old French extension (14c.) and directly from Latin extensionem/extentionem (nominative extensio/extentio), noun of action from past participle stem of extendere (see extend). In a concrete sense, "extended portion of something" (a railroad, etc.), from 1852. Telephone sense is from 1906.

Online Etymology Dictionary, © 2010 Douglas Harper

extension in Medicine




The act of straightening or extending a flexed limb.
A pulling or dragging force exerted on a limb in a distal direction.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

extension in Science



Mathematics A set that includes a given and similar set as a subset.
Computer Science A set of characters that follow a filename and are separated from it by a period, used to identify the kind of file.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.