backfire

American  

[bak-fahy^uhr] / ˈbækˌfaɪər /

verb (used without object)

backfired, backfiring

1. (of an internal-combustion engine) to have a loud, premature explosion in the intake manifold.

2. to bring a result opposite to that which was planned or expected.

   The plot backfired.

   Synonyms:

   bomb, flop, boomerang, miscarry

3. to start a fire deliberately in order to check a forest or prairie fire by creating a barren area in advance of it.

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noun

1. (in an internal-combustion engine) premature ignition of fuel in the intake manifold.

2. an explosion coming out of the breech of a firearm.

3. a fire started intentionally to check the advance of a forest or prairie fire.

backfire British  

/ ˌbækˈfaɪə /

verb

1. (of an internal-combustion engine) to emit a loud noise as a result of an explosion in the inlet manifold or exhaust system

2. (of an endeavour, plan, etc) to have an unwanted effect on its perpetrator

   his plans backfired on him

3. to start a controlled fire in order to halt an advancing forest or prairie fire by creating a barren area

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noun

1. 1. an explosion of unburnt gases in the exhaust system

   2. a premature explosion in a cylinder or inlet manifold

2. a controlled fire started to create a barren area that will halt an advancing forest or prairie fire

Etymology

Origin of backfire

An Americanism dating back to 1775–85; back ² + fire

Explanation

Use the word backfire when you talk about the sound a car makes when a small explosion in its exhaust system pops — sometimes as loudly as a gunshot. Hearing a car's backfire can make you jump, because it makes a sharp, shot-like sound. A backfire is usually caused by unburned fuel, and it can be accompanied by a burst of flame and a brief loss of power in the vehicle, as well as a fairly loud noise. The word comes from an American English term that originally referred to a fire deliberately set to slow the progress of a prairie or forest fire.

Example Sentences

Holding one of these ETFs for a long period could backfire, although it has worked out well recently.

From MarketWatch • May 1, 2026

Then again, Patel’s entire stint at the FBI suggests he doesn’t understand that all his efforts to manifest an image of a smart, cool guy that everyone likes are so ham-fisted that they inevitably backfire.

From Salon • Apr. 24, 2026

But unwed couples often make informal arrangements over custody and child support, which can backfire and land them in court years later.

From The Wall Street Journal • Apr. 20, 2026

But that can backfire when the hype does not match the performance - though the loss to the Cherries was just the second home league defeat of the season.

From BBC • Apr. 18, 2026

He was complacent and insecure, daring in the administrative stratagems he employed to bring himself to the attention of his superiors and craven in his concern that his schemes might all backfire.

From "Catch-22" by Joseph Heller

Related Words

• fail
• flop