heater UK /ˈhiːtə/US /ˈhitɚ/ noun8 •A device that produces and radiates heat, typically to raise the temperature of a room or building.Turn on the heater; I'm cold. •A person who heats something, for example in metalworking. •(slang) A fastball, especially one thrown at high velocity.Jones threw a heater under his chin. •(slang, old-fashioned) A handgun.The thug pumped two rounds from his heater into her. •(slang) An extended winning streak.Emmy went on a heater in Las Vegas and came back six thousand dollars richer. •(slang) Synonym of banger (“a powerfully energetic or exceptional song”). •(historical) A medieval European shield having a rounded triangle shape like a clothes iron. •A dead heat; a race in which two or more competitors reach the finish line simultaneously. formsheaters