Source : Webster's Revised Unabridged Dictionary (1913)

Breeches \Breech"es\, n. pl. [OE. brech, brek, AS. br[=e]k, pl.
   of br[=o]c breech, breeches; akin to Icel. br[=o]k breeches,
   ODan. brog, D. broek, G. bruch; cf. L. bracae, braccae, which
   is of Celtic origin. Cf. {Brail}.]
   1. A garment worn by men, covering the hips and thighs;
      smallclothes.

            His jacket was red, and his breeches were blue.
                                                  --Coleridge.

   2. Trousers; pantaloons. [Colloq.]

   {Breeches buoy}, in the life-saving service, a pair of canvas
      breeches depending from an annular or beltlike life buoy
      which is usually of cork. This contrivance, inclosing the
      person to be rescued, is hung by short ropes from a block
      which runs upon the hawser stretched from the ship to the
      shore, and is drawn to land by hauling lines.

   {Breeches pipe}, a forked pipe forming two branches united at
      one end.

   {Knee breeches}, breeches coming to the knee, and buckled or
      fastened there; smallclothes.

   {To wear the breeches}, to usurp the authority of the
      husband; -- said of a wife. [Colloq.]

Buoy \Buoy\, 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.

   {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} 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.

Source : WordNet®

breeches buoy
     n : a life buoy in the form of a ring with short breeches for
         support; used to transfer people from a ship