Merriam-Webster Collegiate Dictionary - alarm

 I. noun  also alarum  Etymology: Middle English ~e, alarom, from Middle French ~e, from Old Italian all'arme, literally, to the arms  Date: 14th century  1. (usually alarum) archaic a call to arms the angry trumpet sounds alarum — Shakespeare  2. a signal (as a loud noise or flashing light) that warns or alerts; also a device that signals set the ~ to wake me at seven  3. sudden sharp apprehension and fear resulting from the perception of imminent danger  4. a warning notice  Synonyms: see fear  II. transitive verb  also alarum  Date: 1651  1. disturb, excite  2. to give warning to  3. to strike with fear  4. to equip with an ~  • ~ingly adverb