Also: appreciation. Increase in the external value of a currency in terms of other currencies. In a system of fixed or bloc-linked exchange rates, revaluation is effected through legal or official increases in the parity of a currency against the other currencies or the key currency (formerly against gold). In the case of flexible or floating exchange rates, appreciation is the result of a rise in the exchange rate on the currency market in response to supply and demand. Opposite: devaluation.