What does EXTENSION mean?

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 are 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 or more letters; the optional second part of a PC computer filename“most applications provide extensions for the files they create”
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”