Geometry . a plane figure bounded by two radii and the included arc of a circle.

a mathematical instrument consisting of two flat rulers hinged together at one end and bearing various scales.

Machinery . 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.

Military . a designated defense area, usually in a combat zone, within which a particular military unit operates and for which it is responsible.

Astronomy . 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 distinct part, esp. of society or of a nation's economy

the housing sector; the educational sector.

a section or zone, as of a city.

Computers . a portion of a larger block of storage, as 1 / 128 of a track or disk.

to divide into sectors.

noun

whole

noun

category , district , division , part , precinct , quarter , region , stratum , zone , area , section