NOUN (2)

1. an official lowering of a nation's currency; a decrease in the value of a country's currency relative to that of foreign countries;

2. the reduction of something's value or worth;

WordNet (r) 3.0 (2006):

devaluation
    n 1: an official lowering of a nation's currency; a decrease in
         the value of a country's currency relative to that of
         foreign countries
    2: the reduction of something's value or worth