alarm

UK: /əˈlɑː^rm/ US: /əˈlɑrm/ ,(ə lärm′)

WordReference Random House Learner's Dictionary of American English © 2025

a•larm /əˈlɑrm/   n. 

1. a sudden fear or feeling of anxiety due to the awareness of danger;
   fright:
   [uncountable] jumped up in alarm.
2. any sound, outcry, or information intended to warn of approaching danger:
   [countable] The townspeople raised the alarm.
3. an automatic device that serves to arouse or warn of danger:
   [countable] The smoke alarm went off at 4 a.m.

v. [~ + object]

4. to make fearful or apprehensive;
   frighten:
   The news of the invasion alarmed the neighboring countries.
5. to warn of danger.
6. to equip with an alarm or alarms, as in case of fire or robbery.

WordReference Random House Unabridged Dictionary of American English © 2025

a•larm  (ə lärm′), n. 

1. a sudden fear or distressing suspense caused by an awareness of danger; apprehension;
   fright.
2. any sound, outcry, or information intended to warn of approaching danger:
   Paul Revere raced through the countryside raising the alarm that the British were coming.
3. an automatic device that serves to call attention, to rouse from sleep, or to warn of fire, smoke, an intruder, etc.
4. a warning sound;
   signal for attention.
5. Animal Behavior any sound, outcry, chemical discharge, action, or other signal that functions to draw attention to a potential predator.
6. Sport [Fencing.] an appeal or a challenge made by a step or stamp on the ground with the advancing foot.
7. [Archaic.] a call to arms.

v.t. 

8. to make fearful or apprehensive;
   distress.
9. to warn of danger;
   rouse to vigilance and swift measures for safety.
10. to fit or equip with an alarm or alarms, as for fire, smoke, or robbery:
    to alarm one's house and garage.

• Old Italian allarme, noun, nominal from phrase all'arme to (the) arms. See arm²
• Middle French
• Middle English alarme, alarom 1350–1400

a•larm′a•ble, adj. 
a•larm•ed•ly  (ə lär′mid lē), adv.  Synonyms

• 1. consternation; terror, panic. See fear. 
• 8. See frighten. 

Collins Concise English Dictionary © HarperCollins Publishers::

alarm / əˈlɑːm/ verb (transitive)

1. to fill with apprehension, anxiety, or fear
2. to warn about danger; alert
3. to fit or activate a burglar alarm on a house, car, etc

noun

1. fear or terror aroused by awareness of danger; fright
2. apprehension or uneasiness
3. a noise, signal, etc, warning of danger
4. any device that transmits such a warning: a burglar alarm
5. the device in an alarm clock that triggers off the bell or buzzer
6. short for alarm clock
7. a call to arms

Etymology: 14th Century: from Old French alarme, from Old Italian all'arme to arms; see arm²

aˈlarming adjective