A Linear motor is an electrically-powered motor that have had its stator and rotor “unrolled” so that instead of producing a torque (rotation) it produces a linear force along its length.
Unlike rotary motors, which cause thrust through spinning elements, linear induction motors produce their thrust in a straight line. Their thrust is caused through the interaction of magnetic fields within the motors, by magnetic attraction and repulsion.
In a synchronous motor the rate of movement of the magnetic field is controlled, usually electronically, to track the motion of the rotor.