Definition - Extension

extension |ikˈsten sh ən|noun1 a part that is added to something to enlarge or prolong it; a continuation : the railroad's southern extension.• a room or set of rooms added to an existing building.• the action or process of becoming or making something larger : the extension of the president's powers.• an application of an existing system or activity to a new area : direct marketing is an extension of telephone selling.• an increase in the length of time given to someone to hold office, complete a project, or fulfill an obligation.• Computing an optional suffix to a file name, typically consisting of a period followed by several characters, indicating the file's content or function.2 (also extension cord) a length of electric cord that permits the use of an appliance at some distance from a fixed socket.• an extra telephone on the same line as the main one.• a subsidiary telephone in a set of offices or similar building, on a line leading from the main switchboard but having its own additional number.3 [usu. as adj. ] instruction by a university or college for students who do not attend full time : extension courses.4 ( extensions) lengths of real or artificial hair woven into a person's own hair to create a long hairstyle : the type of female with with big trunk jewelry and extensions in her hair.5 the action of moving a limb from a bent to a straight position : seizures with sudden rigid extension of the limbs.• the muscle action controlling this : triceps extension.• Ballet the ability of a dancer to raise one leg above the waist, or an instance of this : she has amazing extension | he could perform 180-degree extensions.• Medicine the application of traction to a fractured or dislocated limb or to an injured or diseased spinal column to restore it to its normal position.• the lengthening of a horse's stride within a particular gait.6 Logic the range of a term or concept as measured by the objects that it denotes or contains, as opposed to its internal content. Often contrasted withintension .• Physics & Philosophy the property of occupying space; spatial magnitude :nature, for Descartes, was pure extension in space.