Extension

Extension may refer to:
 * Extension (kinesiology), a movement of a joint in which one part of the body is moved away from another.
 * Extension (metaphysics), the property of taking up space
 * Extension (semantics), the set of things to which a property applied
 * Extension (mathematics); an extension of some structure is another structure which contains the original structure
 * Extension (geology)
 * Extension (telephone), an internal telephone line attached to a PBX or Centrex system
 * Extension (computing), a computer program that is not useful in its own right but designed to be incorporated in another piece of software
 * Tension (physics)
 * System Extension, a particular type of this software on the classic Mac OS
 * Extension (Mozilla), this type of software for Firefox and other Mozilla projects
 * Extension (community development), the building of community capacity by outsiders, for instance, agricultural extension
 * Extension (cheerleading), a stunt in which a flyer is held in the air by the bases' fully extended arms
 * Extension, the classical name for the Mc1r gene.
 * Extension (music), a set of notes that fit outside the standard range
 * Extension, BC is a small former coal-mining village near Nanaimo, BC, Canada
 * Enamel extension in dentistry
 * Extension cable
 * Extensive property, in physics, a property which depends on the system size or the amount of material in the system
 * Extension school, a school for continuing education
 * Filename extension, a suffix to the name of a computer file applied to show its format
 * Hair extensions, strands of hair added to supplement a person's existing hair
 * Eyelash extensions
 * Extensions the 1979 album by The Manhattan Transfer

Extension (Begriffsklärung) Extensión Extension エクステンション