Helical polarization of an electromagnetic wave in which (a) the electric field vector rotates in a counterclockwise direction as it advances in the direction of propagation, as seen by an observer looking in the direction of propagation and (b) the tip of the electric field vector advances like a point on the thread of a left-hand screw, the normal screw being a right-hand screw, when entering a mated fixed nut or tapped hole. Synonym  left helical polarization. See also  electromagnetic wave,  electric field,  electric field vector,  helical polarization,  point,  polarization,  propagation,  right-hand helical polarization,  vector,  wave.