alarm UK /əˈlɑːm/US /əˈlɑɹm/noun 7verb 5forms 5phrases 1 noun7 •A summons to arms, as on the approach of an enemy.Arming to answer in a night alarm. — 1602 •a device that tells people there is danger, usually by making a loud noiseThe fire alarm is located high on the wall to prevent tampering. •A mechanical device for awaking people or rousing their attention.The clock radio is a friendlier version of the cold alarm by the bedside. •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. — 1611 •An instance of an alarm ringing, beeping or clanging, to give a noise signal at a certain time.Last night's alarm turned out to be nothing, but it was terrifying at the time. •Sudden surprise with fear or terror caused by the apprehension of danger; a feeling of heightened alertness to risk.His actions caused alarm among all the other people in the store, who hurried to leave. •A sudden attack; a disturbance.Lord Marshal, command our officers-at-arms Be ready to direct these home alarms. — 1595 verb5 •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. •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. •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. •To keep in excitement; to disturb. •To call to arms for defense. formsalarmed · alarming · alarmeth · alarms · alarmest Phrases with alarm false alarmA warning signal (such as the call of sentry, the ringing of a bell, or the shriek of a siren) which turns out to have been given erroneously.