"Inflation is a sustained increase in the aggregate price level. Hyperinflation is very high inflation. Although the threshold is arbitrary, economists generally reserve the term 'hyperinflation' to describe episodes when the monthly inflation rate is greater than 50 percent. At a monthly rate of 50 percent, an item that cost $1 on January 1 would cost $130 on January 1 of the following year." Read more.HyperinflationMichael K. SalemiThe Concise Encyclopedia of Economics. Via the Library of Economics and Liberty.