extension

noun

• 1a part that is added to something to enlarge or prolong it:the railway’s southern extension
• a room or rooms added to an existing building: they hope to demolish the store and build a bar extension
• (extensions) lengths of artificial hair woven into a person’s own hair to create a very long hairstyle.
• [mass noun] the action or process of enlarging or extending something: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 additional period of time given to someone to hold office or fulfil an obligation: the initial term of appointment is for one year, but an extension of two years is envisaged
• British permission granted to licensed premises for the sale of alcoholic drinks until later than usual: drinks were served until the early hours of the morning, without any extension having been granted
• Computing an optional suffix to a filename, typically consisting of a full stop followed by several characters, indicating the file’s content or function.

• 2 (British also extension lead or cable; US also extension cord) a length of electric cable which permits the use of appliances at some distance from a fixed socket.

• 3a subsidiary telephone on the same line as the main one: you can listen on the extension in the bedroom
• a subsidiary telephone in a large building, on a line leading from the main switchboard but having its own additional number: contact Liz McDonald on extension 3514

• 4 [mass noun] the action of moving a limb from a bent to a straight position:seizures with sudden rigid extension of the limbs
• Ballet the ability of a dancer to raise one leg above their waist, especially to the side:she has amazing extension
• Medicine the application of traction to a fractured or dislocated limb or to an injured spinal column to restore it to its normal position.
• the lengthening of a horse’s stride at a particular pace.

• 5 [as modifier] denoting instruction by a university or college arranged for people who are not full-time students:a postgraduate extension course

• 6 Logic the range of a term or concept as measured by the objects which it denotes or contains. Often contrasted with intension.

• 7 Physics & Philosophy the property of occupying space:nature, for Descartes, was pure extension in space