A coin is a small, flat, round In plural, it is commonly used as synonym for units of banknotes and coins. More of metal alloy (or combination of metals) used primarily as Money that is legally valid for the payment of debts and must be accepted for that purpose when offered. Each jurisdiction determines what is legal tender, but essentially it is anything which when offered (“tendered”) in payment of a debt extinguishes the debt. There is no obligation on the creditor to accept the tendered payment, but the act of tendering the payment in legal tender discharges the debt. More. Issued by government, they are standardised in weight and composition and are produced at ‘mints’.