noun

• A section.
• A zone; a designated area.
• (military) An area designated by boundaries within which a unit operates, and for which it is responsible.
• (military) One of the subdivisions of a coastal frontier.
• (science fiction) a fictional region of space designated for navigational or governance purposes.
• (geometry) Part of a circle, extending to the center; circular sector.
• (computer hardware) A fixed-sized unit (traditionally 512 bytes) of sequential data stored on a track of a digital medium.
• (calculation) An instrument consisting of two rulers of equal length joined by a hinge.
• A field of economic activity.
• (engineering) A toothed gear whose face is the arc of a circle.
• (motor racing) A fixed, continuous section of the track, such that sectors do not overlap but all sectors make up the whole track.
• (climbing) An area of a crag, consisting of various routes