hyperinflation \hyperinflation\ n.
   an unusually rapid rate of monetary inflation, as when prices
   rise more than 100 per cent per year.

   Note: A famous example occurred in Germany after the first
         World War, reaching its peak in the period 1923. When
         the hyperinflation ended by 1924, the value of the mark
         had decreased by more than one trillion times compared
         to its value in 1914. Periods of lesser hyperinflation
         have occurred in many other countries, as in Russia in
         1994.
         [PJC]