"Quid" is a slang term used in the United Kingdom to refer to the British pound sterling (£), the currency of the UK. It is used in much the same way that "buck" is used to refer to a dollar in the United States.
Quid is the common slang term for the British pound and the word is almost never pluralized. Other terms that refer to a pound include Smacker, Fiver for the £5 note, Tenner for the £10 note, and Dosh.
Buck is an informal reference to $1 that likely traces its origins to the American colonial period, when deerskins (buckskins) were commonly traded for goods. The term is now used to refer to the U.S. dollar both domestically and internationally, and in currency trading, can even refer to the $1 million trades.
The term quid survived Irish independence and now refers to Euros. So if someone says, “that'll be 10 quid”, you'll know you owe them a “tenner” — another Irish slang word for a 10 Euro bill.
A pound comprised twenty Shillings, commonly called 'bob', which was a lovely old slang word. It was 'bob' irrespective of how many shillings there were: no-one ever said 'fifteen bobs' - this would have been said as 'fifteen bob'.
"Sawbuck" is a slang term historically used for a U.S. $10 bill because two ornate Roman numeral Xs were on the backside of the 10-dollar bill issued during the Civil War. Interbank forex dealers may use the term for a $10 million transaction.
The word buck as a term for the U.S. dollar dates back to the 1700s, when deer hides, or buckskins, were often used in trade on the American frontier. Settlers and traders in sparsely populated regions relied on bartering, and buckskins were durable, valuable, and widely accepted.
Two bits is an old slang term for 25 cents. It's based on the sense of the word bit that refers to one eighth of a U.S. dollar, or 12 ½ cents. However, monetary amounts counted in bits were only ever given in multiples of two, as in two bits and six bits.
A slang name for a shilling was a "bob" (plural as singular, as in "that cost me two bob"). The first recorded use was in a case of coining heard at the Old Bailey in 1789, when it was described as cant, "well understood among a certain set of people", but heard only among criminals and their associates.
