The Collaborative International Dictionary of English v.0.48:

Couch'e \Cou`ch['e]"\ (k??`sh?"), a. [F., p. p. of coucher. See
   Couch, v. t. ] (Her.)
      (a) Not erect; inclined; -- said of anything that is
          usually erect, as an escutcheon.
      (b) Lying on its side; thus, a chevron couch['e] is one
          which emerges from one side of the escutcheon and has
          its apex on the opposite side, or at the fess point.
          [1913 Webster]