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

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

In some cases, letting your spouse take care of the finances can backfire.

From The Wall Street Journal • Apr. 19, 2026

Greek authorities have strongly opposed vaccination, arguing that the antibodies they create can backfire by giving false signals of infection.

From Barron's • Mar. 30, 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

I stood in front of her, shaking all over, hands at my sides, martyrlike, fully aware of the dramatic moment that might backfire but willing to take the chance.

From "When I Was Puerto Rican" by Esmeralda Santiago

Related Words

• fail
• flop