What is another word for paper money?

Bill of exchange

a written order to pay a particular amount of money to a person or organization on a particular date:

Cash

money in the form of notes or coins:
to pay in cash / to make payments in cash

Bill

a piece of paper money
a ten-dollar bill

Fiduciary currency

banknotes and coins in circulation

Note / Banknote

a piece of paper money
a €20 note