[andrewla]

Sometimes "debasing" is used to describe the deliberate attempts to devalue money, either by printing more money, or, in earlier times, actually decreasing the amount of precious metals in favor of base metals in minted coins.

There's not really a term for deliberate attempts to increase the value of the currency (as this is a policy goal not really pursued by modern central banks, as deflation is considered to be bad). Demurrage is a related concept, but rarely used in this sense.