1) Axis 1) Dividing line 2) It splits in two 
[music] In diatonic set theory, a bisector divides the octave approximately in half and may be used in place of a generator to derive collections for which structure implies multiplicity is not true such as the ascending melodic minor, harmonic minor, and octatonic scales. Well formed generated collections generators and bisectors coincide,...
• (n.) One who, or that which, bisects; esp. (Geom.) a straight line which bisects an angle.
synchronous time-division multiplex equipment permitting the transmission of character signals corresponding to two start-stop transmissions of the same nominal modulation rate on a transmission channel for this same modulation rate so that the actual character transfer rate is thereby doubled
Bi·sec'tor noun One who, or that which, bisects; esp. (Geom.) a straight line which bisects an angle. 
a line or plane that bisects an angle or line segment.