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

Once someone has formed an opinion, debunking their belief can backfire, driving them to commit even more strongly to their mistake.

From Salon • Apr. 13, 2026

It’s a move that could backfire for the artificial-intelligence start-up.

From Barron's • Apr. 3, 2026

The NFL is taking proactive steps to limit the possibility of a work stoppage involving the referees’ union, but could the league’s plans backfire?

From Los Angeles Times • Apr. 1, 2026

The pressure is now on CEO Vinai Venkatesham - previously at Arsenal - sporting director Johan Lange, and the Lewis family, who are over-seeing affairs, as the gamble of Tudor's appointment continues to backfire.

From BBC • Mar. 24, 2026

A jeep started up with a backfire directly outside and roared away.

From "Catch-22" by Joseph Heller

Related Words

• fail
• flop