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Synonyms

backfire

American  
[bak-fahyuhr] / 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.

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

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

noun

    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

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of backfire

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

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

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

“You only have so many tries” suggests his attempts to help could backfire; that language is inflammatory and shaming at worst and unhelpful at best.

From MarketWatch • Feb. 27, 2026

It’s true that forced treatment doesn’t always get the desired outcome, and can backfire if it makes the person more resistant to treatment.

From Los Angeles Times • Feb. 21, 2026

In many Mende stories the spider is the character that tricks other animals to get what he wants, but his tricks always backfire on him.

From "A Long Way Gone: Memoirs of a Boy Soldier" by Ishmael Beah

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.