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.

Definitions of alarm

n a device that signals the occurrence of some undesirable event

alarm system, warning device
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automobile horn, car horn, hooter, horn, motor horn
a device on an automobile for making a warning noise
burglar alarm
a warning device that is tripped off by the occurrence of a burglary
fire alarm, smoke alarm
an alarm that is tripped off by fire or smoke
an alarm device that makes a loud warning sound
an acoustic device producing a loud often wailing sound as a signal or warning
air horn
a pneumatic horn
a warning device consisting of a horn that generates a loud low tone
claxon, klaxon
a kind of loud horn formerly used on motor vehicles
shofar, shophar
an ancient musical horn made from the horn of a ram; used in ancient times by the Israelites to sound a warning or a summons; used in synagogues today on solemn occasions
Type of:
an instrumentality invented for a particular purpose

n an automatic signal (usually a sound) warning of danger

alarum, alert, warning signal
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a small explosive device that is placed on a railroad track and fires when a train runs over it; the sound of the explosion warns the engineer of danger ahead
air alert
the warning signal that begins a period of preparation for an enemy air attack
burglar alarm
a loud warning signal produced by a burglar alarm
fire alarm
a shout or bell to warn that fire has broken out
foghorn, fogsignal
a loud low warning signal that can be heard by fogbound ships
a noise made by the driver of an automobile to give warning;
red flag
a flag that serves as a warning signal
a warning signal that is a loud wailing sound
alarm bell, tocsin
the sound of an alarm (usually a bell)
Type of:
sign, signal, signaling
any nonverbal action or gesture that encodes a message

n a clock that wakes a sleeper at some preset time

alarm clock
Type of:
a timepiece that shows the time of day

n fear resulting from the awareness of danger

consternation, dismay
Type of:
fear, fearfulness, fright
an emotion experienced in anticipation of some specific pain or danger (usually accompanied by a desire to flee or fight)

v warn or arouse to a sense of danger or call to a state of preparedness

“The empty house alarmed him”
make aware of
Type of:
notify of danger, potential harm, or risk

v fill with apprehension or alarm; cause to be unpleasantly surprised

appal, appall, dismay, horrify
strike with horror or terror
Type of:
affright, fright, frighten, scare
cause fear in

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