In economics, cash is money in the physical form of currency, such as banknotes and coins. In book-keeping and financial accounting, cash is current assets comprising currency or currency equivalents that can be accessed immediately or near-immediately (as in the case of money market accounts). Cash is seen either as a reserve for payments, in case of a structural or incidental negative cash flow or as a way to avoid a downturn on financial markets. Etymology. The English word cash originally meant 'money box', and later came to have a secondary meaning 'money'.
https://en.wikipedia.org/wiki/Cash