planchette

A small plank.
(spiritualism) A type of Ouija board. (A small tablet of wood supported on casters and having a pencil attached. The characters produced by the pencil on paper, while the hand rests on the instrument and it is allowed to move, are sometimes interpreted as of oracular or supernatural import.)
A plane table.
(chiefly) One of the round colored dots pressed into paper money, used to distinguish authentic currency from counterfeit currency.