"Polarisation" is defined as the cofinement of the vibrations of the wave in only one plane and the removal of the vibrations in the other perpendicualar plane of the electromagnetic wave. But the e.m. wave is defined as a wave in which the electic vetors are restricted in one plane only where as the magnetic vector is vibrating in the other plane, i.e,. the em wave is itself is polasrised only as per above definition. In that case what does further polaristion of the wave mean? Removing the vibrations in the other perpendicular plane means removing the magnetic vector? Also if we assume that the electric field has components in all possible directions and out of these vibrations, those in one plane are removed and those in a plane perpendicular to it is retained, will it lead to the conclusion that the electric field vector has components parallel to the magnetic field vector also i.e.in the x-z plane ( assume the electric field is vibrating in the x-y plane and the magnetic field in the x-z plane, x-axis being the direction of propagation)? If that is so, will it not violate the very definition of the em wave which says that these are the waves in which electric filed, magnetic field and the direction of propagation all are mutually perpendicular to each other? Will any body kindly clarify these points?