Source : Webster's Revised Unabridged Dictionary (1913)

Schemer \Schem"er\, n.
   One who forms schemes; a projector; esp., a plotter; an
   intriguer.

         Schemers and confederates in guilt.      --Paley.

Source : WordNet®

schemer
     n : a planner who draws up a personal scheme of action [syn: {plotter}]