Definition of "Sector" :

noun: measuring instrument consisting of two graduated arms hinged at one end

noun: a particular aspect of life or activity

"He was helpless in an important sector of his life."

noun: a social group that forms part of the society or the economy

"The public sector."

noun: a portion of a military position

noun: the minimum track length that can be assigned to store information; unless otherwise specified a sector of data consists of 512 bytes

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