a false report of a fire in progress to a fire department.
2.
something that excites unfounded alarm or expectation:
Rumors of an impending transit strike proved to be a false alarm.
Origin
1570-80
Examples from the web for false alarm
Instead, when nearby monkeys dropped their food and ran, the one that had sounded the false alarm moved in to scoop up the bounty.
Perhaps at that point, law enforcement personnel might have had reason to believe that this was a false alarm.
If the home-loving citizen would sit down and think about it, he would realize that this is a false alarm.
They were afraid, they believed they were in danger, though maybe it was all a false alarm.
And half of these thefts involved a false alarm that fooled the target into seeking cover from a non-existent threat.
After a false alarm which turned out to be a transmission from an aircraft, no signals of extraterrestrial origin were reported.
It took eight minutes to conclude that it was a false alarm.
Hiller helps the ever-widening group of robbers to outsmart the bank's security system by staging one false alarm after another.
He did not want to sound a false alarm, but the consequences of smallpox could be staggering.
They called off their response to the reported incident after it turned out to be a false alarm.
British Dictionary definitions for false alarm
false alarm
noun
1.
a needless alarm given in error or with intent to deceive
2.
an occasion on which danger is perceived but fails to materialize
Idioms and Phrases with false alarm
false alarm
A warning signal that is groundless, made either by mistake or as a deliberate deception. For example, The rumor that we were all going to get fired was just a false alarm, or Setting off a false alarm is a criminal offense. This expression, first recorded in 1579, today is often used for a report of a nonexistent fire.