From Longman Dictionary of Contemporary Englishfiverfiv‧er /ˈfaɪvə $ -ər/ noun [countable] British English informal PECMONEYa piece of paper money worth five pounds Lend me a fiver, mate?
Examples from the Corpus
fiver• That usually works out at about a fiver a flourish.• The illustrated catalogue costs a fiver, which will get two people into the event.• A pair to fit wellies which reach right up to the knee cost a penny short of a fiver.• He laid out a fiver - and went home counting the cash after Dowie scored twice.• It cost less than a fiver a head - and there wasn't a plate broken all night!• Homeless and down to a fiver.• When I opened it I found neat bundles of fivers, each one with a Bank of Berlin band around it.• He'd got two fivers left, then. 