The Collaborative International Dictionary of English v.0.48:

Down \Down\, a.
   1. Downcast; as, a down look. [R.]
      [1913 Webster]

   2. Downright; absolute; positive; as, a down denial. [Obs.]
      --Beau. & Fl.
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   3. Downward; going down; sloping; as, a down stroke; a down
      grade; a down train on a railway.
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   Down draught, a downward draft, as in a flue, chimney,
      shaft of a mine, etc.

   Down in the mouth, Down at the mouth chopfallen;
      dejected.
      [1913 Webster]