The Collaborative International Dictionary of English v.0.48:

Breeches \Breech"es\ (br[i^]ch"[e^]z), 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.
      [1913 Webster]

            His jacket was red, and his breeches were blue.
                                                  --Coleridge.
      [1913 Webster]

   2. Trousers; pantaloons. [Colloq.]
      [1913 Webster]

   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.]
      [1913 Webster]

WordNet (r) 3.0 (2006):

breeches
    n 1: trousers ending above the knee [syn: breeches, knee
         breeches, knee pants, knickerbockers, knickers]

Easton's 1897 Bible Dictionary:

Breeches
   (Ex. 28:42), rather linen drawers, reaching from the waist to a
   little above the knee, worn by the priests (Ezek. 44:17, 18).