alarm

plural alarms · alternative alarum

1. countableA summons to arms, as on the approach of an enemy.

   Arming to answer in a night alarm.

   c. 1602 (date written), William Shakespeare, “The Tragedie of Troylus and Cressida”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, →OCLC, [Act I, scene iii]

2. countableAny 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, The Holy Bible, […] (King James Version), London: […] Robert Barker, […], →OCLC, Joel 2:1

   1 more example

   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.

   1859, Charles Dickens, The Haunted House

3. countableA device intended to warn or give notice of approaching danger.

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

4. countableA sudden attack; a disturbance.

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

   1595 December 9 (first known performance), William Shakespeare, “The Life and Death of King Richard the Second”, in Mr. William Shakespeares Comedies, Histories, & Tragedies: Published According to the True Originall Copies (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, →OCLC, [Act I, scene i]

   1 more example

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

   1725, Homer, “Book I”, in [Elijah Fenton], transl., The Odyssey of Homer. […], volume I, London: […] Bernard Lintot, →OCLC, page III

5. countableSudden 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.

   1 more example

   Alarm and resentment spread through the camp.

   1849–1861, Thomas Babington Macaulay, chapter I, in The History of England from the Accession of James the Second, volume (please specify |volume=I to V), London: Longman, Brown, Green, and Longmans, →OCLC

6. countableA mechanical device for awaking people or rousing their attention.

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

7. countableAn 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.

present singular third person alarms · participle present alarming · participle past alarmed · past alarmed · alternative alarum

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

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

   2 more examples

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

   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; […]

   1838, Joseph Sheridan Le Fanu, Passage in the Secret History of an Irish Countess

3. transitiveTo 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.

   1985 March 21, National Transportation Safety Board, “2.2 Environmental Factors”, in Aircraft Accident Report: United Airlines Flight 663, Boeing 727-222, N7647U, Denver, Colorado, May 31, 1984, page 39

4. transitiveTo 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. transitiveTo keep in excitement; to disturb.