Matrix (Matrice).----This word is used by some numismatic writers to signify the die, square, or punch; that is to say, the mass of hardened metal, on which is engraved or sunk, the inverse way, the type of the medal, in order to impress it, the right way, on the blank which is exposed to its stroke. The word by which the Romans designated the die, or as the French call it the coin of the medal, is not known.