1. Sudden fear or concern caused by the realization of danger or an impending setback. See Synonyms at fear.
2. A warning of existing or approaching danger: The committee's report issued an alarm about the dangerous condition of the town's buildings.
3. A device that is used to warn of danger by means of a sound or signal: a fire alarm.
4. The sounding mechanism of an alarm clock: The alarm went off at 6:30.
5. A call to arms.
tr.v. a·larmed, a·larm·ing, a·larms
1. To fill with alarm or anxious concern. See Synonyms at frighten.
2. To give warning to: "The soldiers ... killed every dog within three miles to prevent a bark that would alarm the enemy" (William Least Heat-Moon).
3. To equip with or protect by an alarm: The dormitory doors are alarmed from 7:00 PM to 7:00 AM.
[Middle English, from Old French alarme, from Old Italian allarme, from all'arme, to arms : alla, to the (from Latin ad illa : ad, to; see AD- + illa, neuter pl. of ille, that, the; see al-1 in the Appendix of Indo-European roots) + arme, arms (from Latin arma; see ar- in the Appendix of Indo-European roots).]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2016 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The American Heritage Dictionary Blog
Check out our blog, updated regularly, for new words and revised definitions, interesting images from the 5th edition, discussions of usage, and more.
American Heritage Dictionary Products
The American Heritage Dictionary, 5th Edition
The American Heritage Dictionary of Idioms
The American Heritage Roget's Thesaurus
Curious George's Dictionary
The American Heritage Children's Dictionary
The American Heritage Dictionary of Indo-European Roots
The American Heritage Student Grammar Dictionary
The American Heritage Desk Dictionary + Thesaurus
The American Heritage Science Dictionary
The American Heritage Dictionary of Business Terms
The American Heritage Student Dictionary
The American Heritage Essential Student Thesaurus