Nouns

(n)alarm, dismay, consternationfear resulting from the awareness of danger
(n)alarm, warning device, alarm systema device that signals the occurrence of some undesirable event
(n)alarm, alert, warning signal, alaruman automatic signal (usually a sound) warning of danger
(n)alarm clock, alarma clock that wakes a sleeper at some preset time

Verbs

(v)dismay, alarm, appal, appall, horrifyfill 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”
(v)alarm, alertwarn 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”