What Is a Smoking Gun? – Idiom, Origin & Meaning

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Danielle McLeod

Danielle McLeod is a highly qualified secondary English Language Arts Instructor who brings a diverse educational background to her classroom. With degrees in science, English, and literacy, she has worked to create cross-curricular materials to bridge learning gaps and help students focus on effective writing and speech techniques. Currently working as a dual credit technical writing instructor at a Career and Technical Education Center, her curriculum development surrounds student focus on effective communication for future career choices.

Idiomatic words and phrases have different meanings than their literal use. We use them to create analogies for a more interesting or understandable message. They are used in both speech and writing but can create confusion when the audience is unaware of the idiom’s meaning.

A smoking gun is an idiomatic phrase with an understandable literal and descriptive figurative use. It was first used literally in 19th-century fictional literature and has since become a well-recognized phrase in speech and writing.

Let’s take a look at its origins and use so you can use it in your own material.

What Does a Smoking Gun Mean?

What Is a Smoking Gun Idiom Origin Meaning

The idiomatic phrase “smoking gun” refers to a piece of evidence that is irrefutably true—a fact or thing that proves conclusively that a crime has occurred or that someone is guilty.

A smoking gun is a figurative term derived from the literal fact that if someone is found holding a smoking gun, it is reasonable to assume that person has recently fired that gun, whether the shooting was witnessed or not.

For example:

  • The evidence was a smoking gun, linking his location to the thefts and allowing the detective to make a strong case for his arrest.
  • She regards the documents as a possible smoking gun in the investigation into procuring illegal substances by the company serving as a front for the crime syndicate.
  • But when presented with the smoking gun of the surveillance videos, they backed out of the lawsuit and chose to accept the consequences of the insurance fraud.

Origins of the Phrase Smoking Gun

Smoking Gun Ngram
Smoking gun usage trend.

The literal use of the phrase smoking gun was first documented in 1843 in Alexander Marlinsky’s fiction story, Ammalát Bek, published in Blackwood’s Edinburgh Magazine:

“Ammalát leaped from his horse, and, resting his arms on his yet smoking gun, looked for several moments steadfastly in the face of the murdered man; as if endeavouring to prove to himself that he feared not that fixed gaze, those fast-dimming eyes—that fast-freezing blood.”

It was likely a term used even before being seen in print, but variations began to grow in their use as seen in the 1893 Sherlock Holmes story The “Gloria Scott” written by Sir Arthur Conan Doyle:

“The chaplain stood with a smoking pistol in his hand….”

The first documentation of its figurative use as a way to point out irrefutable guilt occurred in 1966 in the American College Health Association, Proceedings of the Annual Meeting:

“Let’s avoid “smoking gun decisions” in the next few years by adequate preparation and organization, recognizing the strength of our well-established convictions, standards and principles.”

It was likely used figuratively before this, but by putting it into print, it kick-started its use in mainstream English usage.

The idiom’s popularity following this usage is highlighted even further in the Watergate investigation during the 1970s when a particular White House tape recording was dubbed the Smoking-Gun Tape. In the recording, Nixon tells Halderman to order the CIA and the FBI to stop investigating the Watergate break-in under the pretext of protecting national security. At the Watergate Congressional Hearing, Representative Barber Conable said the new evidence “looked like a smoking gun.”

Let’s Review

A smoking gun is an idiomatic phrase to point out that a piece of evidence is the information needed to prove a crime has occurred or there is irrefutable guilt involved in a crime.

It is derived from the literal use of the term that points out that the person holding an actual gun, recently discharged, is the guilty party in a shooting.

The phrase came into literal use in writing in the mid-19th century and became popular as an idiom in the 1970s during the Watergate investigation and related scandals.

Enjoyed reading about this idiom? Check out some others we covered: