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alarm

American  
[uh-lahrm] / əˈlɑrm /

noun

  1. a sudden fear or distressing suspense caused by an awareness of danger; apprehension; fright.

    Synonyms:
    panic, terror, consternation
  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. 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.


verb (used with object)

  1. to make fearful or apprehensive; distress.

  2. to warn of danger; rouse to vigilance and swift measures for safety.

  3. to fit or equip with an alarm or alarms, as for fire, smoke, or robbery.

    to alarm one's house and garage.

alarm British  
/ əˈlɑːm /

verb

  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

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

noun

  1. fear or terror aroused by awareness of danger; fright

  2. apprehension or uneasiness

    the idea of failing filled him with alarm

  3. a noise, signal, etc, warning of danger

  4. any device that transmits such a warning

    a burglar alarm

    1. the device in an alarm clock that triggers off the bell or buzzer

    2. short for alarm clock

  5. archaic a call to arms

  6. fencing a warning or challenge made by stamping the front foot

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
alarm Idioms  

Usage

What does alarm mean? Alarm is a sudden feeling of fear or suspense caused by an awareness of danger, as in The pirates boarding the ship filled the captain with alarm. An alarm is any sound or cry that is meant to alert someone. It can also be the device that produces the alarm, such as an alarm clock. Sounding the alarm means to activate a siren, bell, or a repeated verbal call, usually projected from a speaker of some kind. To alarm someone is to make them fearful or distressed, as in My parents alarmed me when they started talking about moving south. To alarm also means to warn someone about danger. Example: Not to alarm you, but I feel like I might need to go to the emergency room.

Related Words

See fear. See frighten.

Other Word Forms

Etymology

Origin of alarm

1350–1400; Middle English alarme, alarom < Middle French < Old Italian allarme, noun from phrase all'arme to (the) arms. See arm 2

Explanation

On a clock, the alarm can be set to go off at a certain time to wake nearby sleepers. You should always check the alarm on the clock at a hotel because a previous guest may have it set to go off in the middle of the night. The noun alarm refers to a signal that is meant to rouse, alert, or awaken someone. On April 18, 1775, William Dawes, Paul Revere, and several others rode from Boston to Lexington, Massachusetts to raise the alarm that the British were coming. As a verb, alarm means to be filled with anxiety or apprehension. You may become alarmed if your children become too quiet. Never a good sign — they are probably up to something mischievous.

Keep Reading on Vocabulary.com

Vocabulary lists containing alarm

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

And in October the Steve Reich Ensemble and Alarm Will Sound will commemorate the composer’s 90th birthday with four performances at the Park Avenue Armory in New York.

From The Wall Street Journal • Apr. 22, 2026

Alarm clocks that shock you and make you do math.

From MarketWatch • Mar. 4, 2026

Asked about an end to early-morning starts, she joked: "What is a lie in? I have no idea. Alarm clocks will be a thing of the past."

From BBC • Jan. 27, 2026

Last week, the Alarm Phone charity, which runs a hotline for migrants stranded in the Mediterranean, reported a fatal shooting at a boat it said was carrying 113 migrants southeast of Malta.

From Barron's • Oct. 18, 2025

Alarm lit up her face like a candle.

From "The Darkest Minds" by Alexandra Bracken