- a plane figure bounded by two radii and the included arc of a circle.
- a distinct part, especially of society or of a nation's economy: the housing sector; the educational sector.
- a section or zone, as of a city.
- a designated defense area, usually in a combat zone, within which a particular military unit operates and for which it is responsible.
- a mathematical instrument consisting of two flat rulers hinged together at one end and bearing various scales.
- a device used in connection with an index plate, consisting of two arms rotating about the center of the plate and set to indicate the angle through which the work is indexed.
- an instrument shaped like a sector of a circle, having a variable central angle and sights along the two straight sides, for measuring the angular distance between two celestial bodies.
- a portion of a larger block of storage, as 1/128 of a track or disk.
- to divide into sectors.
- a part or subdivision, esp of a society or an economy
- either portion of a circle included between two radii and an arc. Area: 1/2 r ²θ, where r is the radius and θ is the central angle subtended by the arc (in radians)
- a measuring instrument consisting of two graduated arms hinged at one end
- a part or subdivision of an area of military operations
- the smallest addressable portion of the track on a magnetic tape, disk, or drum store
