| 1. | Nautical. a vertical blade at the stern of a vessel that can be turned horizontally to change the vessel's direction when in motion. |
| 2. | Aeronautics. a movable control surface attached to a vertical stabilizer, located at the rear of an airplane and used, along with the ailerons, to turn the airplane. |
| 3. | any means of or device for governing, directing, or guiding a course, as a leader or principle: His ideas provided a rudder for the new company. |
