The Collaborative International Dictionary of English v.0.48:

Buoy \Buoy\ (bwoi or boi; 277), n. [D. boei buoy, fetter, fr.
   OF. boie, buie, chain, fetter, F. bou['e]e a buoy, from L.
   boia. "Boiae genus vinculorum tam ferreae quam ligneae."
   --Festus. So called because chained to its place.] (Naut.)
   A float; esp. a floating object moored to the bottom, to mark
   a channel or to point out the position of something beneath
   the water, as an anchor, shoal, rock, etc.
   [1913 Webster]

   Anchor buoy, a buoy attached to, or marking the position
      of, an anchor.

   Bell buoy, a large buoy on which a bell is mounted, to be
      rung by the motion of the waves.

   Breeches buoy. See under Breeches.

   Cable buoy, an empty cask employed to buoy up the cable in
      rocky anchorage.

   Can buoy, a hollow buoy made of sheet or boiler iron,
      usually conical or pear-shaped.

   Life buoy, a float intended to support persons who have
      fallen into the water, until a boat can be dispatched to
      save them.

   Nut buoy or Nun buoy, a buoy large in the middle, and
      tapering nearly to a point at each end.

   To stream the buoy, to let the anchor buoy fall by the
      ship's side into the water, before letting go the anchor.


   Whistling buoy, a buoy fitted with a whistle that is blown
      by the action of the waves.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Buoy \Buoy\, v. t. [imp. & p. p. Buoyed; p. pr. & vb. n.
   Buoying.]
   1. To keep from sinking in a fluid, as in water or air; to
      keep afloat; -- with up.
      [1913 Webster]

   2. To support or sustain; to preserve from sinking into ruin
      or despondency.
      [1913 Webster]

            Those old prejudices, which buoy up the ponderous
            mass of his nobility, wealth, and title. --Burke.
      [1913 Webster]

   3. To fix buoys to; to mark by a buoy or by buoys; as, to
      buoy an anchor; to buoy or buoy off a channel.
      [1913 Webster]

            Not one rock near the surface was discovered which
            was not buoyed by this floating weed. --Darwin.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Buoy \Buoy\, v. i.
   To float; to rise like a buoy. "Rising merit will buoy up at
   last." --Pope.
   [1913 Webster]

WordNet (r) 3.0 (2006):

buoy
    n 1: bright-colored; a float attached by rope to the seabed to
         mark channels in a harbor or underwater hazards
    v 1: float on the surface of water
    2: keep afloat; "The life vest buoyed him up" [syn: buoy,
       buoy up]
    3: mark with a buoy

Moby Thesaurus II by Grady Ward, 1.0:

121 Moby Thesaurus words for "buoy":
   Carling float, Mae West, Roman candle, aid to navigation, alarm,
   amber light, balefire, balsa, balsa raft, beacon, beacon fire,
   bear up, bell, bell buoy, blinker, blue peter, bob, boom,
   breeches buoy, buoy up, caution light, cork, cork jacket,
   ejection capsule, ejection seat, ejector seat, elevate, flare,
   float, float high, fog bell, fog signal, fog whistle, foghorn,
   glance, go light, gong buoy, green light, hearten, heliograph,
   high sign, hold up, international alphabet flag,
   international numeral pennant, keep up, kick, leer, life belt,
   life buoy, life jacket, life net, life preserver, life raft,
   life ring, life vest, lifeboat, lifeline, lift, lollipop,
   marker beacon, nod, nudge, parachute, parachute flare, pilot flag,
   poke, police whistle, pontoon, quarantine flag, radio beacon, raft,
   raise, red flag, red light, ride high, rocket, rubber dinghy,
   safety belt, sailing aid, semaphore, semaphore flag,
   semaphore telegraph, sign, signal, signal beacon, signal bell,
   signal fire, signal flag, signal gong, signal gun, signal lamp,
   signal light, signal mast, signal post, signal rocket, signal shot,
   signal siren, signal tower, siren, spar buoy, stop light, support,
   surfboard, sustain, the nod, the wink, touch, traffic light,
   traffic signal, upbear, uphold, uplift, upraise, waft, watch fire,
   water wings, white flag, wigwag, wigwag flag, wink, yellow flag



Bouvier's Law Dictionary, Revised 6th Ed (1856):

BUOY. A piece of wood, or an empty barrel, floating on the water, to show
the place where it is shallow, to indicate the danger there is to
navigation. The act of Congress, approved the 28th September, 1850, enacts,
" that all buoys along the coast, in bays, harbors, sounds, or channels,
shall be colored and numbered, so that passing up the coast or sound, or
entering the bay, harbor or channel, red buoys with even numbers, shall be
passed on the starboard hand, black buoys, with uneven numbers, on the port
hand, and buoys with red and black stripes on either hand. Buoys in channel
ways to be colored with alternate white and black perpendicular stripes."