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treachery

American  
[trech-uh-ree] / ˈtrɛtʃ ə ri /

noun

treacheries plural
  1. violation of faith; betrayal of trust; treason.

    Antonyms:
    loyalty
  2. an act of perfidy, faithlessness, or treason.


treachery British  
/ ˈtrɛtʃərɪ /

noun

  1. the act or an instance of wilful betrayal

  2. the disposition to betray

"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

Related Words

See disloyalty.

Etymology

Origin of treachery

First recorded in 1175–1225; Middle English trecherie, from Middle French, Old French, from trech(ier) “to deceive” ( see trick) + -erie -ery

Explanation

Treachery is trickery, cheating, and deceit, like the treachery of your former friend who only stuck around until he stole your girlfriend and turned the whole grade against you. The noun treachery comes from the Old French word trechier, “to cheat.” Many a corrupt government or dictator has been accused of treachery: deceiving the people and abusing their trust. Greed is a common cause of treachery — with the promise of wealth, people can be tempted to betray their country and even their loved ones, as new celebrities find out when their best friends sell embarrassing secrets to the tabloids.

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Vocabulary lists containing treachery

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.

Most of the unhappy denizens of Dante’s imagined hell are being eternally tormented for specific moral crimes in categories covering lust, gluttony, greed, anger, heresy, violence, fraud and treachery.

From Salon • Mar. 8, 2026

It’s a sprawling tale of divine corruption and human treachery that ends with the world being purified by fire and flood.

From The Wall Street Journal • Feb. 12, 2026

The war has been rife with accusations of treachery from the very beginning.

From BBC • Apr. 21, 2025

“The treachery of your tears is no use to fight injustice,” read one.

From New York Times • Jun. 5, 2024

That I may never forgive, in chief his treachery to Sir Gareth.

From "The Once and Future King" by T. H. White

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