false alarm

American  

noun

1. 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.

---

false alarm British  

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

---

false alarm Idioms  

1. 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.

---

Etymology

Origin of false alarm

First recorded in 1570–80

Example Sentences

This misinterpretation activates the cell's innate immune system, creating a false alarm that can lead to inflammation and disease.

From Science Daily • Feb. 27, 2026

The ShakeAlert computer system that warns about the imminent arrival of shaking from earthquakes sent out a false alarm Thursday morning for a magnitude 5.9 temblor in Carson City, Nev., that did not actually happen.

From Los Angeles Times • Dec. 4, 2025

I see some information about cops scrambling, but an editor says it’s a false alarm and not to worry about it.

From Slate • Jun. 17, 2025

If there is no indication of a false alarm or if a second detector sends a warning, fire alarms are then normally activated throughout the building.

From BBC • Jan. 22, 2025

Because yeah, it was a false alarm, but I know it felt real to Dylan.

From "What If It's Us" by Becky Albertalli and Adam Silvera