fiver
n. countable C2 Proficiency UK //fˈaɪvɐ// fiv·er
n. a slang name for a five-pound note in the UK. You use this when talking about money in a casual way.
n. a five-pound banknote in the United Kingdom.
I only have a fiver in my pocket.
He reached into his jacket and pulled out a fiver to pay for the coffee.
While the digital economy has reduced the need for physical cash, the fiver remains a common denomination for small, everyday purchases in many parts of the country.
From five + -er (measurement suffix) or + -er (“supporter”).