alarm

(noun) fear resulting from the awareness of danger. Synonyms: dismay, consternation.

(noun) a device that signals the occurrence of some undesirable event. Synonyms: warning device, alarm system.

(noun) an automatic signal (usually a sound) warning of danger. Synonyms: alert, warning signal, alarum.

(noun) a clock that wakes a sleeper at some preset time. Synonyms: alarm clock.

(verb) fill with apprehension or alarm; cause to be unpleasantly surprised. Synonyms: dismay, appal, appall, horrify. Examples: "I was horrified at the thought of being late for my interview." "The news of the executions horrified us."

(verb) warn or arouse to a sense of danger or call to a state of preparedness. Synonyms: alert. Examples: "The empty house alarmed him." "We alerted the new neighbors to the high rate of burglaries."