smoking gun

noun

1. indisputable proof or evidence of a crime.

smoking gun

noun

1. a piece of irrefutable incriminating evidence

Word History and Origins

Origin of smoking gun¹

First recorded in 1970–75

Idioms and Phrases

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]

Example Sentences

In other words, no smoking gun - just an uneasy wait for answers that may never even fully emerge.

From BBC

But the nagging feeling persists there is more to this situation, some kind of smoking gun to explain how it all ended like this.

From BBC

Republicans deflect and deny until the smoking gun is produced.

From Salon

"Facing clear evidence of peril, we cannot wait for the final proof - the smoking gun - that could come in the form of a mushroom cloud," Bush said in an October 2002 televised speech.

From BBC

Chilton alleges that there are two smoking guns that support his case.

From Los Angeles Times