[n] a device that signals the occurrence of some undesirable event
[n] a clock that wakes sleeper at preset time
[n] an automatic signal (usually a sound) warning of danger
[n] fear resulting from the awareness of danger
[v] warn or arouse to a sense of danger or call to a state of preparedness; "The empty house alarmed him"; "We alerted the new neighbors to the high rate of burglaries"
[v] fill with apprehension or alarm; cause to be unpleasantly surprised; "I was horrified at the thought of being late for my interview"; "The news of the executions horrified us"
alarm clock, alarm system, alarum, alert, alert, appal, appall, consternation, dismay, dismay, horrify, warning device, warning signal