smoking gun

American  

noun

1. indisputable proof or evidence of a crime.

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smoking gun British  

noun

1. a piece of irrefutable incriminating evidence

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smoking gun Idioms  

1. Something that serves as indisputable evidence or proof, especially of a crime. For example, There is no smoking gun in the Oval Office; the President had no role in tampering with the evidence. This expression alludes to the smoke coming from a recently discharged firearm, a normal occurrence until the invention of smokeless powder. [Mid-1900s]

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Etymology

Origin of smoking gun

First recorded in 1970–75

Example Sentences

But they were, with remarkable frequency, also a smoking gun.

From Slate • Feb. 18, 2026

But the RBA still needs a smoking gun in the CPI data, with most attention on the trimmed mean core inflation.

From The Wall Street Journal • Jan. 23, 2026

There is no definitive smoking gun in this lawsuit.

From BBC • Dec. 16, 2025

Scott Griffiths of the Melbourne School of Psychological Sciences said a "smoking gun research study" was unlikely to emerge soon to prove the harms of social media.

From Barron's • Dec. 1, 2025

The tape of Nixon and his staff plotting to use the CIA to block the FBI’s investigation of the Watergate break-in proved to be the smoking gun prosecutors were looking for.

From "Most Dangerous: Daniel Ellsberg and the Secret History of the Vietnam War" by Steve Sheinkin