A piece of paper money (especially one issued by a central bank) WordNet 3.0 & Open English WordNet

A banknote—also called a bill, paper money, or simply a note—is a type of negotiable promissory note, made by a bank or other licensed authority, payable to the bearer on demand. Wikipedia

Greenbacks were emergency paper currency issued by the United States during the American Civil War that were printed in green on the back. Wikipedia

A form of cash currency, also known as bill in the United States and Canada Wikipedia Disambiguation

A fiat currency issued during the American Civil War Wikipedia Disambiguation

Form of physical currency made of paper Wikidata

Form of paper currency Wikidata

A piece of paper money. OmegaWiki

A promissory note issued by a bank, payable at a given time to a specific beneficiary. Wiktionary

A writing binding the signer or signers to pay a certain sum at a future day or on demand, with or without interest, as may be stated in the document; a bill of exchange. In the United States, it is usually called a note, a note of hand, or a promissory note. Wiktionary

Bill of exchange. Wiktionary (translation)

A unit of American currency issued during the Civil War by the Treasury Department. Wiktionary

A piece of paper money; a banknote. Wiktionary