1. a five-dollar bill
Usage: informal; chiefly American
2. a five-pound note
Usage: informal; chiefly British

Examples

• Can you lend me a fiver for lunch?
• I found a fiver in my old jacket pocket.
• The coffee costs a fiver at that fancy café.
• He tipped the waiter a fiver.
• She paid with a fiver and got change back.
• The parking meter only accepts coins, not fivers.