The full, official name, pound sterling, (plural: pounds sterling) is used mainly in formal contexts and also when it is necessary to distinguish the United Kingdom currency from other currencies with the same name. Otherwise the term pound is normally used. The currency name is sometimes abbreviated to just sterling, particularly in the wholesale financial markets, but not when referring to specific amounts; for example, "Payment is accepted in sterling" but never "These cost five sterling". The abbreviations "ster." or "stg." are sometimes used. The term British pound is commonly used in less formal contexts, although it is not an official name of the currency. A common slang term is quid (singular and plural) which is thought to derive from the Latin phrase "quid pro quo"