Noun

• 1. a mutually agreed delay in the date set for the completion of a job or payment of a debt;

  "they applied for an extension of the loan"

• 2. act of expanding in scope; making more widely available;

  "extension of the program to all in need"

• 3. the spreading of something (a belief or practice) into new regions

• 4. an educational opportunity provided by colleges and universities to people who not enrolled as regular students

• 5. act of stretching or straightening out a flexed limb

• 6. a string of characters beginning with a period and followed by one to three letters; the optional second part of a PC computer filename;

  "most applications provide extensions for the files they create"

  "most BASIC files use the filename extension .BAS"

• 7. the most direct or specific meaning of a word or expression; the class of objects that an expression refers to;

  "the extension of `satellite of Mars' is the set containing only Demos and Phobos"

• 8. the ability to raise the working leg high in the air;

  "the dancer was praised for her uncanny extension"

  "good extension comes from a combination of training and native ability"

• 9. amount or degree or range to which something extends;

  "the wire has an extension of 50 feet"

• 10. an additional telephone set that is connected to the same telephone line

• 11. an addition to the length of something

• 12. an addition that extends a main building