planchet
Concise Oxford English Dictionary © 2008 Oxford University Press:
planchet /ˈplan(t)ʃɪt/
▶noun a plain metal disc from which a coin is made.
– origin C17: dimin. of earlier planch ‘slab of metal’, from OFr. planche ‘plank, slab’.
'planchet' also found in these Oxford entries:

