propeller

Short definition from Wiktionary

Noun

1. 1
   One who, or that which, propels.
2. 2
   A mechanical device with evenly-shaped blades that turn on a shaft to push against air or water, especially one used to propel an aircraft or boat.
3. 3
   A steamboat thus propelled; a screw steamer.
4. 4
   A spinnerbait.