Definitions

from The American Heritage® Dictionary of the English Language, 5th Edition.

  • adjective Guilty of or characterized by betrayal of confidence or trust; perfidious.
  • adjective Characterized by unforeseen or hidden hazards; dangerous or deceptive.

from The Century Dictionary.

  • 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 the GNU version of the Collaborative International Dictionary of English.

  • adjective 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 Wiktionary, Creative Commons Attribution/Share-Alike License.

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

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

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

Etymologies

from Wiktionary, Creative Commons Attribution/Share-Alike License

From treacher

Examples

  • 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 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

  • 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

  • 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

Comments

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  • -- 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

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

    August 8, 2007

  • 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