rudder

Etymology

From Middle English rodder, rother, ruder, from Old English rōþor (“oar, rudder”), from Proto-West Germanic *rōþr, from Proto-Germanic *rōþrą (“oar, rudder”) (compare Dutch and West Frisian roer, German Ruder), from Proto-Germanic *rōaną, from Proto-Indo-European *h₁reh₁- (“to row”) + Proto-Germanic *-þrą, *-þraz, instrumental suffix. Akin to Old English rōwan (“to row”). More at rōwan, -þor.

noun

1. (nautical) 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. (aeronautics) 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. A riddle or sieve.
4. (figurative) That which resembles a rudder as a guide or governor; that which guides or governs the course.
   Hudibras For rhyme the rudder is of verses.