Definition of "Alarm" :
noun: a device that signals the occurrence of some undesirable event
noun: a clock that wakes a sleeper at some preset time
noun: an automatic signal (usually a sound) warning of danger
noun: fear resulting from the awareness of danger
verb: warn or arouse to a sense of danger or call to a state of preparedness
"The empty house alarmed him."
verb: fill with apprehension or alarm; cause to be unpleasantly surprised