A warning device is a tool used to alert people of potential danger. Common warning devices include sirens (5 letters), which emit a loud sound, telltales (8 letters), which are visual indicators, alarms (5 letters), which can be both audible and visual, horns (4 letters), which are loud and often used in vehicles, flares (5 letters), which are bright lights used to signal distress, RADAR (5 letters), which is used to detect objects, firealarms (9 letters), which are used to detect smoke, and smokealarms (10 letters), which are used to detect fires.