This seems to be a name for one of the various types of Azimuth Thrusters.

ship design and maneuverability This expedient is often not sufficient for low-speed maneuvering. For this reason, many ships are fitted with a "bow thruster," a propeller mounted in a transverse tunnel near the bow. This thruster can push the bow sideways without producing forward motion. If a similar thruster is fitted near the stern, a ship can be propelled sideways-or even rotated in place