Entry 1 sense Webster, 1913 Bisector /bī'sĕktər/ · Bi·sec·tor · IPA /ˈbaɪˌsɛktɚ/ 01 n. One who, or that which, bisects; esp. (Geom.) a straight line which bisects an angle. 1. One who, or that which, bisects; esp. (Geom.) a straight line which bisects an angle.(Geom.)