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

See Examples For:

smoking gun

But the reported result has not been officially confirmed, and even a confirmed positive would not necessarily be the smoking gun it might appear to be.

From BBC ● Aug. 15, 2026

"I think Joseph has found the smoking gun," Howell said.

From Science Daily ● Jul. 6, 2026

And in a place like the United States, where everyone is in pursuit of power, walking around with a smoking gun puts a target on your back.

From Salon ● Jul. 4, 2026

Jackson’s ex-wife Debbie Rowe was meant to take the stand as a smoking gun for the prosecution but instead revealed no new information and came to Jackson’s defense.

From Los Angeles Times ● Jun. 5, 2026

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