Dictionary.net

Something claimed by royal right, as a charge on metal brought to the royal mint to be coined; a share of the receipts of a business taken in payment for the use of a right, as a copyright or patent.

A governmental charge for coining bullion.

The difference between the cost of bullion and the nominal value of the coin made from it.

A royalty or a commission on sales.

n. Something claimed or taken by virtue of sovereign prerogative; specifically, a certain toll or deduction on bullion brought to the mint to be coined.