2. Something that causes people to wrongly believe that a bad or dangerous thing is going to happen: The report in the news which indicated that the company was going out of business was just another one of those false alarms.
2. A security device installed in property; especially, a house or car, to make a warning sound if a break-in or theft is attempted: The new system for the crime-prevention alarms were very loud and so they would help protect the store from criminal invasions.
3. Clocks or watches that will sound off when set: There are time mechanisms that provide alarms for people.
4. Fear caused by the perception of or the sudden sense of imminent danger: Chrissy's parents have expressed alarm about her safety when she goes hiking in the mountains.
5. Etymology: from the old French summons to battle a l'arme!, "to arms!" It seems to be a far cry from the modern alarm clock; yet, that is actually the content of the word's development."
A l'arme! was first the call itself and then, in the form alarme, it became the name of this sudden summons.
The English alarm, which comes from this origin, first had the same meaning, but gradually broadened to indicate a warning signal of any kind of danger, and then the apparatus for giving this signal; such as, a fire alarm.
It is interesting to also note that alarm has developed an additional meaning: the fear which results from a warning of danger.