planchet

from WordNet (r) 3.0 (2006)

planchet
    n 1: a flat metal disk ready for stamping as a coin [syn:
         {planchet}, {coin blank}]

from The Collaborative International Dictionary of English v.0.48

Planchet \Planch"et\, n. [F. planchette a small board, dim. of
   planche. See {Planch}.]
   A flat piece of metal; especially, a disk of metal ready to
   be stamped as a coin.
   [1913 Webster]