What is the meaning of extension?

noun

• A mutually agreed delay in the date set for the completion of a job or payment of a debt.
  • usage: "they applied for an extension of the loan"
• Act of expanding in scope; making more widely available.
  • usage: "extension of the program to all in need"
• The spreading of something (a belief or practice) into new regions.
  • synonyms: propagation
• An educational opportunity provided by colleges and universities to people who are not enrolled as regular students.
  • synonyms: extension service, university extension
• Act of stretching or straightening out a flexed limb.
• A string of characters beginning with a period and followed by one or more letters; the optional second part of a PC computer filename.
  • usage: "most applications provide extensions for the files they create"; "most BASIC files use the filename extension. BAS"
  • synonyms: filename extension, file name extension
• The most direct or specific meaning of a word or expression; the class of objects that an expression refers to.
  • usage: "the extension of `satellite of Mars' is the set containing only Demos and Phobos"
  • synonyms: reference, denotation
• The ability to raise the working leg high in the air.
  • usage: "the dancer was praised for her uncanny extension"; "good extension comes from a combination of training and native ability"
• Amount or degree or range to which something extends.
  • usage: "the wire has an extension of 50 feet"
  • synonyms: lengthiness, prolongation
• An additional telephone set that is connected to the same telephone line.
  • synonyms: telephone extension, extension phone
• An addition to the length of something.
  • synonyms: elongation
• An addition that extends a main building.
  • synonyms: annex, annexe, wing