Cag ‧ ney, James /ˈkæɡni/ BrE AmE
(1899–1986) a US film actor known for appearing as a ↑ gangster (=a member of a violent group of criminals) in films such as The Public Enemy (1931) and White Heat (1949). He is supposed to have said ‘You dirty rat’ in one of his films and people often remember this phrase when they think of him.