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

Historical records reveal there were several close calls in the early ’80s, including the 1983 Soviet nuclear false alarm that could have triggered a nuclear war.

From Slate • Feb. 2, 2026

However, at 06:38 on Friday, he explained the "unknown vessel" was a false alarm.

From BBC • Aug. 8, 2025

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

If something really bad happened, the police would think it was another false alarm and not come.

From "The Old Willis Place" by Mary Downing Hahn