1560s, in geometry, "a section of a circle between two radii," from Late Latin sector "section of a circle," in classical Latin "a cutter, one who cuts," from sectus, past participle of secare "to cut" (from PIE root *sek- "to cut"). Sector translated Greek tomeus in Latin editions of Archimedes.
By 1715 of any figure having the shape of a sector; the meaning "area, division" (without regard to shape) is by 1920, perhaps generalized from a World War I military sense (1916) of "part of a front," based on a circle centered on a headquarters. The meaning "a branch of an economy" is by 1937. As a verb from 1884, "divide into sectors." Related: Sectored; sectoral; sectorial.
updated on March 25, 2022