Propeller

n.
  1. One who, or that which, propels.
  2. A contrivance for propelling a steam vessel, usually consisting of a screw placed in the stern under water, and made to revolve by an engine; a propeller wheel.
  3. A steamboat thus propelled; a screw steamer.
    4. Propeller wheel ,
    the screw, usually having two or more blades, used in propelling a vessel.