Русско-англо-русский юридический словарь

Currency intervention, also known as currency manipulation, exchange rate intervention or foreign exchange market intervention, is the purchase or the sale of the currency on the exchange market by the fiscal authority or the monetary authority, in order to influence the value of the domestic currency. (Wikipedia)

In macroeconomics and modern monetary policy, a devaluation is an official lowering of the value of a country's currency within a fixed exchange-rate system, in which a monetary authority formally sets a lower exchange rate of the national currency in relation to a foreign reference currency or currency basket. (Wikipedia)