From Longman Dictionary of Contemporary Englishcold (hard) cashcold (hard) cashMONEY American English money in the form of paper money and coins rather than cheques or credit cards → cold
Examples from the Corpus
cold (hard) cash• After a year, the igloo-shaped stadium has cost the citizens $ 20 million in very cold cash.• The other driving force is cold cash and order books.• No cold cash in the Nugent icebox, however, so I moved on.• Luckily, the chatter of cold hard cash later persuaded the state to sell the name to the highest bidder. 