seigniorage:

The term “seigniorage” originates from the Old French word “seigneuriage,” a derivative of “seigneur,” meaning “lord” or “master.” The root of this term lies in the feudal system, where the seigneur, or lord, had various rights and privileges, one of which was the authority to mint coins.

In medieval times, the right to coin money was often an exclusive privilege of the sovereign or feudal lord. This privilege allowed the lord to retain the difference between the value of the precious metal in the coins and the nominal value assigned to them. This difference or profit from minting coins came to be known as “seigniorage.”

Over time, as monetary systems evolved, the concept of seigniorage also developed. It shifted from being associated with the profits from minting metal coins to its current understanding in modern economies, where it represents the profit made by governments from issuing currency, especially in fiat money systems.

Thus, the etymology of “seigniorage” reflects its historical roots in feudal systems and its evolution alongside changes in monetary practices and economic structures.