Anything which is generally acceptable as a means of settling debts. In present-day economics money normally consists of libabilities of the government (notes and coin) and of the banks (bank accounts), i.e. money consists of claims held by individuals on banks and the government, these claims being generally acceptable as a means of payment.
This use of claims as money is a feature of realitvely acceptable system of finance and credit. In less well-developed systems, arcticles which possessed intristic value (piece of gold, cows or cigarettes) were used as a means of payment.This difference reflects the importance of economic stability and well-developed financial institutions, since the use of money which has no instristic value of itsown depends on confidence that it will be universally acceptable in exchange for goods.
Reference: The Penguin Business Dictionary, 3rd edt.