alarm

noun

1. (countable, uncountable)A summons to arms, as on the approach of an enemy.

   “Arming to answer in a night alarm.”

2. (countable, uncountable)Any sound or information intended to give notice of approaching danger; a warning sound to arouse attention; a warning of danger.

   “Sound an alarm in my holy mountain.”

   “She went about the house in a state of real terror, and yet lied monstrously and wilfully, and invented many of the alarms she spread, and made many of the sounds we heard.”

3. (countable, uncountable)A device intended to warn or give notice of approaching danger.

   “The fire alarm is located high on the wall to prevent tampering.”

4. (countable, uncountable)A sudden attack; a disturbance.

   “Lord Marshal, command our officers-at-arms Be ready to direct these home alarms.”

   “Is it then true, as distant rumours run, that crowds of rivals for thy mother's charms thy Palace fill with insults and alarms?”

5. (countable, uncountable)Sudden surprise with fear or terror excited by the apprehension of danger; a feeling of heightened alertness to risk; in the military use, commonly, sudden apprehension of being attacked by surprise.

   “Alarm and resentment spread through the camp.”

6. (countable, uncountable)A mechanical device for awaking people, or rousing their attention.

   “The clock radio is a friendlier version of the cold alarm by the bedside.”

7. (countable, uncountable)An instance of an alarm ringing, beeping or clanging, to give a noise signal at a certain time.

   “You should set the alarm on your watch to go off at seven o'clock.”

verb

1. (transitive)To call to arms for defense.
2. (transitive)To give (someone) notice of approaching danger or necessary action; to rouse to vigilance; to put on the alert.

   “The sudden drop in temperature should alarm you into taking precautions.”

   “Her illness started to alarm the doctors, who ordered more tests.”

   “When the carriage drew up in the grass-grown court yard before the hall-door, two lazy-looking men, whose appearance well accorded with that of the place which they tenanted, alarmed by the obstreperous barking of a great chained dog, ran out from some half-ruinous out-houses, and took charge of the horses; […]”

3. (transitive)To produce a warning of approaching danger or necessary action; to emit a signal intended to rouse a recipient to vigilance or put them on the alert.

   “The tower cab supervisor and various pilots stated that the LLWAS system frequently alarms because of the thunderstorm activity present, and that airspeed losses are common as a result of convective wind shear.”

4. (transitive)To surprise with apprehension of danger; to fill with anxiety in regard to threatening evil; to excite with sudden fear.

   “The loud bang in the hallway seemed to alarm everyone in the building.”

5. (transitive)To keep in excitement; to disturb.