definition of Extention by The Free Dictionary




1. The act of extending or the condition of being extended: the extension of the subway into the suburbs.

2. The amount, degree, or range to which something extends or can extend: The wire has an extension of 50 feet.


a. The act of straightening or extending a limb.

b. The position assumed by an extended limb.

4. A length of human or synthetic hair attached to the scalp or to strands of hair close to the scalp to add volume, length, or color.

5. Medicine The application of traction to a fractured or dislocated limb to restore the normal position.


a. An addition that increases the area, influence, operation, or contents of something: an extension for the vacuum cleaner; built a new extension onto the hospital wing.

b. An additional telephone connected to a main line.


a. An allowance of extra time, as for the repayment of a debt.

b. The period of this extra time: three months’ extension on the loan.

8. The property of an object by which it occupies space.


a. A program in a university, college, or school offering academic instruction to nontraditional students, such as working adults, who cannot attend classes at the usual place and time.

b. A publicly funded program offering such instruction along with information on agriculture, home economics, and business.

10. Computers A set of characters that follow a filename and are separated from it by a period, used to identify the kind of file: In most operating systems, filenames having the extension .EXE are executable files.

11. Logic The class of objects designated by a specific term or concept; denotation.

12. Mathematics A set that includes a given and similar set as a subset.

[Middle English extensioun, from Old French extension, from Latin extēnsiō, extēnsiōn-, from extēnsus, past participle of extendere, to extend; see extend.]

ex·ten′sion·al adj.

American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.




1. the act of extending or the condition of being extended

2. something that can be extended or that extends another object

3. the length, range, etc, over which something is extended; extent

4. (Telecommunications) an additional telephone set connected to the same telephone line as another set or other sets

5. (Building) a room or rooms added to an existing building

6. (Commerce) a delay, esp one agreed by all parties, in the date originally set for payment of a debt or completion of a contract

7. (General Physics) the property of matter by which it occupies space; size

8. (Physiology)

a. the act of straightening or extending an arm or leg

b. its position after being straightened or extended

9. (Medicine) med a steady pull applied to a fractured or dislocated arm or leg to restore it to its normal position. See also traction3
10. (Education)

a. a service by which some of the facilities of an educational establishment, library, etc, are offered to outsiders

b. (as modifier): a university extension course.

11. (Logic) logic

a. 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 Phobos. Compare intension1a

b. conservative extension a formal theory that includes among its theorems all the theorems of a given theory

[C14: from Late Latin extensiō a stretching out; see extend]

Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(ɪkˈstɛn ʃən)


1. an act or instance of extending.

2. the state of being extended.

3. that by which something is extended; an addition: a four-room extension to a house.

4. an enlargement in scope or degree: an extension of knowledge.

5. the total range of something; compass.

6. an increase in length of time given one to meet an obligation, as the repayment of a debt.

7. the property of a body by which it occupies space.


a. the act of straightening a limb.

b. the position that a limb assumes when it is straightened.

9. an additional telephone that operates on a principal line.

10. a program by which an institution, as a university, provides instruction or other services away from the regular location or outside regular hours.

11. Logic. the class of things to which a term is applicable; denotation. Compare intension (def. 5).

12. Computers. Also called file extension. one or more characters at the end of a filename, usu. following a period, used to indicate the type of file.

[1350–1400; < Latin extēnsiō span]

ex•ten′sion•al, adj.

ex•ten′sion•al•ly, adv.

ex•ten′sion•less, adj.

Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.

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