The Collaborative International Dictionary of English v.0.48:

Down \Down\, v. t. [imp. & p. p. Downed; p. pr. & vb. n.
   Downing.]
   To cause to go down; to make descend; to put down; to
   overthrow, as in wrestling; hence, to subdue; to bring down.
   [Archaic or Colloq.] "To down proud hearts." --Sir P. Sidney.
   [1913 Webster]

         I remember how you downed Beauclerk and Hamilton, the
         wits, once at our house.                 --Madame
                                                  D'Arblay.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

downed \downed\ adj.
   1. knocked down.
      [WordNet 1.5]

   2. (Football) touched to the ground, thus ending the play; --
      of a football.
      [PJC]