| Noun | 1. | alarm system - a device that signals the occurrence of some undesirable eventautomobile horn, car horn, motor horn, hooter, horn - a device on an automobile for making a warning noise burglar alarm - a warning device that is tripped off by the occurrence of a burglary device - an instrumentality invented for a particular purpose; "the device is small enough to wear on your wrist"; "a device intended to conserve water" smoke alarm, fire alarm - an alarm that is tripped off by fire or smoke horn - an alarm device that makes a loud warning sound siren - an acoustic device producing a loud often wailing sound as a signal or warning |