- measuring instrument consisting of two graduated arms hinged at one end

- a particular aspect of life or activity
"he was helpless in an important sector of his life"

- a body of people who form part of society or economy
"the public sector"

- a portion of a military position

- the minimum track length that can be assigned to store information

- unless otherwise specified a sector of data consists of 512 bytes

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

1. A part of a circle comprehended between two radii and the included arc.

2. A mathematical instrument, consisting of two rulers connected at one end by a joint, each arm marked with several scales, as of equal parts, chords, sines, tangents, etc., one scale of each kind on each arm, and all on lines radiating from the common center of motion. The sector is used for plotting, etc., to any scale.

3. An astronomical instrument, the limb of which embraces a small portion only of a circle, used for measuring differences of declination too great for the compass of a micrometer. When it is used for measuring zenith distances of stars, it is called a zenith sector.

Dip sector
an instrument used for measuring the dip of the horizon.

Sector of a sphere
or Spherical sector
the solid generated by the revolution of the sector of a circle about one of its radii, or, more rarely, about any straight line drawn in the plane of the sector through its vertex.