rudder

noun

1. 1

   An underwater vane used to steer a vessel. The rudder is controlled by means of a wheel, tiller or other apparatus (modern vessels can be controlled even with a joystick or an autopilot).

2. 2

   A control surface on the vertical stabilizer of a fixed-wing aircraft or an autogyro. On some craft, the entire vertical stabilizer comprises the rudder. The rudder is controlled by foot-operated control pedals.

3. 3

   A riddle or sieve.

4. 4

   That which resembles a rudder as a guide or governor; that which guides or governs the course.