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.

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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

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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.

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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

Weiss is about to get his first face-to-face with Spears, but it’s a false alarm: She thinks Weiss is a production assistant.

From Los Angeles Times • Jun. 9, 2025

What’s a red flag, what’s a false alarm and what’s already a five alarm fire.

From Slate • Jan. 25, 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

He couldn't make the Theorem work, and he realized that his Eureka moment had been a false alarm.

From "An Abundance of Katherines" by John Green