from The American Heritage® Dictionary of the English Language, 4th Edition

  • adj. Marked by betrayal of fidelity, confidence, or trust; perfidious. See Synonyms at faithless.
  • adj. Not to be relied on; not dependable or trustworthy.
  • adj. Marked by unforeseen hazards; dangerous or deceptive: treacherous waters.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • adj. Exhibiting treachery.
  • adj. Deceitful; inclined to betray.
  • adj. Unreliable; dangerous.

from the GNU version of the Collaborative International Dictionary of English

  • adj. Like a traitor; involving treachery; violating allegiance or faith pledged; traitorous to the state or sovereign; perfidious in private life; betraying a trust; faithless.

from The Century Dictionary and Cyclopedia

  • Using treachery; violating allegiance or faith pledged; traitorous to the state or sovereign; perfidious in private life; betraying a trust.
  • Marked by deceitfulness or perfidy; characteristic of a traitor.
  • Having a good, fair, or sound appearance, but worthless or bad in character or quality; deceptive; not to be depended on or trusted.
  • Synonyms Faithless, etc. (see perfidious), recreant, treasonable.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • adj. tending to betray; especially having a treacherous character as attributed to the Carthaginians by the Romans
  • adj. dangerously unstable and unpredictable


from Wiktionary, Creative Commons Attribution/Share-Alike License

From treacher


  • Unless the guides were treacherous, he must sight the minarets of El Obeid soon _Unless the guides were treacherous_!

    For Fortune and Glory A Story of the Soudan War

  • Infuriated by what he calls a treacherous and unacceptable provocation from the diplomatic mission, Cuban communist leader, Fidel Castro began building his response a few days later.

    CNN Transcript Feb 6, 2006

  • Our noble captain did not get rid of his angry looks for some days, and actually wept at what he termed the treacherous conduct of the Admiralty.

    A Sailor of King George

  • Left-wing Philippine groups are planning to hold protests outside the U.S. embassy in Manila on Saturday to denounce what they describe as the "treacherous" negotiations with the United States.

    Reuters: Press Release

  • Their meeting was not cordial, nor such as men, who meet in a desert, should give each other; but I thought they would have parted in peace, until I saw one put his rifle to the other's back, and do what I call a treacherous and sinful murder.

    The Prairie

  • Calling the open-sourcing of software treacherous is a little wildly off base, where is the treachery?

    Did Open Source ever have a halo? : #comments

  • The one absolutely unselfish friend that man can have in this selfish world, the one that never deserts him, the one that never proves ungrateful or treacherous, is his DOG.

    Think Progress » VIDEO: Byrd Takes Frist To School

  • The low-flying cargo planes often had to weave through mountaintops in treacherous weather conditions.

    Remains Returned List WWII

  • The multiple truths of those memories are sometimes difficult, their terrain treacherous, and the stories I heard were not always as simple as heroic master narratives had wanted them to be.

    'I Saw a Nightmare …' Doing Violence to Memory: The Soweto Uprising, June 16, 1976

  • Equally treacherous is the view that the young have always been inscrutable to adults and have always complained about being misunderstood.

    The Apocalypse of Adolescence


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  • adjective: tending to betray

    Even though Jesse James was an outlaw, his killer, Robert Ford, is remembered more for his treacherous actions than for eliminating a criminal and murderer.

    adjective: dangerously unstable and unpredictable

    The bridge built from twine and vine is treacherous to walk across, and so I think I will stay put right here.

    October 19, 2016

  • My dad's favorite word to describe heavy traffic or bad driving conditions. :-)

    August 8, 2007

  • -- The others are putting on their hats, Mr Kernan said. I suppose we can do so too. We are the last. This cemetery is a treacherous place.

    Joyce, Ulysses, 6

    January 1, 2007