Definition – What does Zombie Currency mean?
A zombie currency is a legal currency that is no longer used as the main currency of trade. Zombie currencies are created when severe inflation or hyperinflation occurs and the people begin to use the currencies of other nations or certain goods as the basis of trade. A zombie currency is called so because it is already dead in the minds of the people who are supposed to use it, but has not yet been replaced or revalued.
ForexTerms explains Zombie Currency
Zombie currency is a slang term that began popping up when the Zimbabwean dollar (ZWL) was suffering hyperinflation. The ZWL was being denominated in millions, then billions, and then trillions. Although the currency was still being printed at an alarming rate, anyone that could was using alternate currencies such as the U.S. dollar, the South African rand, the euro and so on. The ZWL was abandoned entirely in 2009, but there is always a chance it will rise from the dead someday.