late 14c., from Anglo-Fr. estendre (late 13c.), from L. extendere "stretch out," from ex- "out" + tendere "to stretch" (see tenet). Related: Extended; extending.
programming To add features to a program, especially through the use of hooks. "Extend" is very often used in the phrase "extend the functionality of a program." Plug-ins are one form of extension. (1997-06-21)