Sector

sek′tur, n. that which cuts: that which is cut off: a portion of the circle between two radii and the intercepted arc: a mathematical instrument for finding a fourth proportional: an astronomical instrument: ( mech. ) a toothed gear, the face of which is the arc of a circle.— adjs. Sec′toral ; Sectō′rial , adapted or intended for cutting.— n. a sci or-tooth. [L. sector — secāre , to cut.]