forty-five UK /ˌfɔːtiˈfaɪv/US /ˌfɔɹtiˈfaɪv/noun 1number 1forms 1 noun1 •A .45-caliber firearm.The robber brandished a forty-five at the cashier to make her empty the till for him. number1 •Cardinal number after forty-four and before forty-six. formsforty-fives
