Also: depreciation. Reduction of the external value of a currency. In a system of fixed exchange rates or bloc currencies, devaluation is effected by the legal or official lowering of the exchange rate (or parity) of a currency in terms of the other currencies (formerly against gold). In the case of flexible or floating exchange rates, depreciation is the result of a decline in the exchange rate on the currency market in synch with supply and demand. Opposite: revaluation.