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

The practice worked in Uncle Sam’s favor, as the Fed lowered its short-term interest rate target by 1.75 percentage points in 2024 and 2025, but it may backfire if the central bank starts hiking.

From Barron's • May 22, 2026

Yet the stunning recent drop in domestic supplies may soon backfire as the summer travel season approaches.

From MarketWatch • May 7, 2026

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

From The Wall Street Journal • Apr. 19, 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

This approach is destined to backfire on me, so I decide to dump the rest of my cereal down the drain, too, and talk nonstop on my way to the door.

From "Please Ignore Vera Dietz" by A.S. King

Related Words

• fail
• flop