As a Noun: 1. A warning device which consists of a rapidly rotating and flashing light (usually red) attached inside buildings onto ceilings or walls, or on the top of emergency vehicles (fire, police, etc). It lights and spins when there is an alarm. English = visual alarm. 2. A warning device which consists of a rapidly rotating and flashing light (usually red) and a long, loud, wailing noise. It is usually located on the top of emergency vehicles (fire, police, etc). English = siren. 3. A warning device that makes a long, loud, wailing noise when there is an alarm. English = siren. As a Verb or Adjective: 1. Of a visual alarm, to warn people of danger by spinning and lighting up. 2. Of an audible alarm, to make a loud noise. English = wail.