Currency devaluation was the process whereby one's currency steadily became worth less than it had been previously.
During the Great Monetary Collapse on Ferenginar, Quark was away and felt helpless knowing that rampant inflation and currency devaluation were affecting his home. In 2372, he assured Miles O'Brien that he knew what it was like to be unable to do anything about protecting a place you loved, comparing this situation to Miles' fears for Earth. Miles was not comforted in the least. (DS9: "Homefront")