The most common example in modern democracies is currency.
In his Commentaries on the Laws of England, William Blackstone defined money as:
"... the medium of commerce.... Money is an universal medium, or common standard, by comparison with which the value of all merchandise may be ascertained; or it is a sign, which represents the respective values of all commodities. Metals are well calculated for this sign ... and a precious metal is still better calculated...."
In Moss v Hancock (1899 2 QB 111, England), Justice Darling adopted these words:
"Money ... (is) that which passes freely from hand to hand throughout the community in final discharge of debts and full payment for commodities, being accepted equally without reference to the character or credit of the person who offers it and without the intention of the person who receives it to consume it or apply it to any other use than in turn to tender it to others in discharge of debts or payment of commodities."
The Supreme Court of Canada, in Re Alberta Statutes (1938 SCR 100), defined money as:
"Any medium which by practice fulfills the function of money and which everyone will accept as payment of a debt is money in the ordinary sense of the word even though it may not be legal tender."