The Collaborative International Dictionary of English v.0.48:

Breech \Breech\, v. t. [imp. & p. p. Breeched; p. pr. & vb. n.
   Breeching.]
   1. To put into, or clothe with, breeches.
      [1913 Webster]

            A great man . . . anxious to know whether the
            blacksmith's youngest boy was breeched. --Macaulay.
      [1913 Webster]

   2. To cover as with breeches. [Poetic]
      [1913 Webster]

            Their daggers unmannerly breeched with gore. --Shak.
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   3. To fit or furnish with a breech; as, to breech a gun.
      [1913 Webster]

   4. To whip on the breech. [Obs.]
      [1913 Webster]

            Had not a courteous serving man conveyed me away,
            whilst he went to fetch whips, I think, in my
            conscience, he would have breeched me. --Old Play.
      [1913 Webster]

   5. To fasten with breeching.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

breeched \breeched\ (br[=e]cht), adj.
   dressed in trousers.

   Syn: pantalooned, trousered.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

breeched
    adj 1: dressed in trousers [syn: breeched, pantalooned,
           trousered]