1. A sudden fear caused by the realization of danger.
2. A warning of existing or approaching danger.
3. An electrical, electronic, or mechanical device that serves to warn of danger by means of a sound or signal.
4. The sounding mechanism of an alarm clock.
5. A call to arms.

1. To fill with alarm; frighten. See synonyms at fear, frighten.
2. To give warning to.

[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) + arme, arms (from Latin arma).]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.