Plank n.
 1. A broad piece of sawed timber, differing from a board only in being thicker. See Board.
 2. Fig.: That which supports or upholds, as a board does a swimmer.
    His charity is a better plank than the faith of an intolerant and bitter-minded bigot.   --Southey.
 3. One of the separate articles in a declaration of the principles of a party or cause; as, a plank in the national platform. [Cant]
 Plank road, or Plank way, a road surface formed of planks. [U.S.]
 To walk the plank, to walk along a plank laid across the bulwark of a ship, until one overbalances it and falls into the sea; -- a method of disposing of captives practiced by pirates.