sector

noun

• 1an area or portion that is distinct from others.
• a distinct part or branch of a nation’s economy or society or of a sphere of activity such as education:the industrial and commercial sector the business sector of the city
• Military a subdivision of an area for military operations.
• Computing a subdivision of a track on a magnetic disk.

• 2the plane figure enclosed by two radii of a circle or ellipse and the arc between them.

• 3a mathematical instrument consisting of two arms hinged at one end and marked with sines, tangents, etc., for making diagrams.