Meaning of EXTENSION in English

I. ikˈstenchən, ek-, in sense 3c “ or estäⁿsyōⁿ noun

( plural extensions -ənz, -ōⁿ(z))

Usage: often attributive

Etymology: Middle English extensioun, from Middle French or Late Latin; Middle French extension, from Late Latin extension-, extensio, from Latin extensus + -ion-, -io -ion


a. : the action of extending or state of being extended : a stretching out or stretching forth : a carrying forward : lengthening, furthering, developing

b. : the action of spreading out (as in area) or state of being spread out : expansion , enlargement , augmentation , increase

c. : something extended


a. : the total range over which something extends or can be extended : compass

the extension of the human mind

b. : denotation 4

plant is a word with wider extension than orchid

— contrasted with intension


a. : the stretching of a fractured or luxated limb so as to restore it to its natural position

b. : the straightening out of a flexed limb

c. : a dance movement in which the leg is extended at an angle to the body ; also : an exercise (as for a ballet dancer) in which this movement is used


a. : a property whereby something occupies or apparently occupies a greater or lesser part of space : spatial magnitude

b. : something marked or delimited by the property of extension

5. : an increase in length of time : increased or continued duration ; specifically : an agreement on or concession of additional time (as for meeting an overdue debt or fulfilling a legal formality)

6. : the making available of the educational opportunities or other resources of an institution by special programs or methods (as evening classes in a university, off-campus instruction centers, correspondence courses, library branches, or bookmobiles) to persons otherwise unable to take advantage of such opportunities and resources ; also : a service or system by which such opportunities or resources are made available


a. : a part that is extended from or attached to a main body or section as an addition, supplement, or enlargement

a house with two extensions

or that is capable of being so extended or attached

a table with side extensions

: a section that forms an additional length

an extension for an electric-light cord

the extension of a railway

: prolongation ; also : something having extensions (as a table)

b. : an extra telephone connected to the principal line

they have a downstairs phone and an extension in each of the bedrooms

8. : an indicated figure or amount: as

a. : a figure transferred or carried forward (as in bookkeeping)

b. : an amount computed (as by multiplying a number of units by the cost of each unit)

extensions on an invoice

II. noun

: a mathematical set (as a field or group) that includes a given and similar set as a subset

Webster's New International English Dictionary.      Новый международный словарь английского языка Webster.