Definition of "alarum"

The rest is the irreducible minimum of poverty's needs: […] an American alarum clock on the shelf above the unused fireplace […]

1912, George Bernard Shaw, “Act I”, in Pygmalion‎

The story struck the depressingly familiar note with which true stories ring in the tried ears of experienced policemen. […] The second note, the high alarum, not so familiar and always important since it indicates the paramount sin in Man's private calendar, took most of them by surprise although they had been well prepared.

1963, Margery Allingham, “Eye Witness”, in The China Governess: A Mystery, London: Chatto & Windus, page 249

Just another forum, then, sounding the usual alarums on the looming threat from global warming?

2008 December 9, Jeff Jacoby, “Skepticism on climate change”, in The International Herald Tribune‎

Come let vs meet them at the mountain foot,And with a ſodaine and an hot alarumDriue all their horſes headlong down the hill.

c. 1587–1588, [Christopher Marlowe], Tamburlaine the Great. […] The First Part […], 2nd edition, part 1, London: […] [R. Robinson for] Richard Iones, […], published 1592; reprinted as Tamburlaine the Great (A Scolar Press Facsimile), Menston, Yorkshire, London: Scolar Press, 1973, (please specify the page)

Alarum within.(stage direction)

c. 1606 (date written), William Shakespeare, “The Tragedie of Macbeth”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act I, scene ii], page 131, column 1

It seems to me that by the same process they are also made less "real" - distinguished, in part, by the physical size of the television screen, which, for all the industry's advances, still shows one a picture of men three inches tall shooting at other men three inches tall, and trivialized, or at least tamed, by the enveloping cozy alarums of the household.

1969, Michael Arlen, Living Room War

On the cable news channels, especially, there were teary-eyed interviews with bystanders; alarums from both the gun control advocates on the one side and the Second Amendment nuts on the other; and--inevitably, inappropriately--debates over what the shooting might mean for this closely-watched Senate race.

2016, Christopher Kelly, The Pink Bus, Mapple Shade, New Jersey: Lethe Press, page 95

Now o're the one halfe World / Nature ſeemes dead, and wicked Dreames abuſe / The Curtain'd ſleepe: Witchcraft celebrates / Pale Heccats Offrings: and wither'd Murther, / Alarum'd by his Centinell, the Wolfe, / Whoſe howle's his Watch, thus with his ſtealthy pace, / With Tarquins rauiſhing ſides, towards his deſigne / Moues like a Ghoſt.

c. 1606 (date written), William Shakespeare, “The Tragedie of Macbeth”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act II, scene i], page 136, column 1