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

  • n. Deliberate breach of faith; calculated violation of trust; treachery: "the fink, whose perfidy was equaled only by his gall” ( Gilbert Millstein).
  • n. The act or an instance of treachery.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. A state or act of violating faith or allegiance; violation of a promise or vow, or of trust reposed; faithlessness; treachery.
  • n. Specifically, in warfare, an illegitimate act of deception, such as using symbols like the Red Cross or white flag to gain proximity to an enemy for purposes of attack.
  • n. A state or act of deceit.

from the GNU version of the Collaborative International Dictionary of English

  • n. The act of violating faith or allegiance; violation of a promise or vow, or of trust reposed; faithlessness; treachery.

from The Century Dictionary and Cyclopedia

  • n. Breach of faith or trust; hase treachery; faithlessness.
  • n. Synonyms See perfidious.

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

  • n. an act of deliberate betrayal
  • n. betrayal of a trust


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

Latin perfidia, from perfidus, treacherous : per-, to destruction; see per- + fidēs, faith.

from Wiktionary, Creative Commons Attribution/Share-Alike License

From Latin perfidus ("faithless, treacherous, false"), from fides ("faith"); related to, for example, English fidelity.


  • But much as she loved England she was very loud in denouncing what she called the perfidy of the mother to the brightest of her children.

    Tales of all countries

  • One that routinely engages in perfidy, intentionally targets civilians, uses hospitals, schools and mosques to hide and fire rockets, transports its soldiers and material using ambulances marked with the red crescent, refuses to abide by a unified command structure, refuses to wear distinctive insignia, .... is not comparable to a “freedom fighter” in any respect except the trivial.

    The Volokh Conspiracy » What’s Going on With Turkey

  • The day the nadir of his perfidy is brought to light, he will effectively have put the lives of hundreds of thousands — maybe even millions of Americans and more worrisome to him — American Interests (“Cha-CHING!”) in exponentially greater jeopardy than before.

    Look 'Pon The Devil's Brow...An Impossibility...

  • I await the response of someone that believes that perfidy is acceptable in killing Mr. Awlaki.

    The Volokh Conspiracy » Opinio Juris Discussions of Targeting of US Citizen

  • In my readings of British history generally, the word perfidy arises quite often.

    On Thursday, the Legg report will be published along with...

  • It would be naive to think that human perfidy is not capable of depriving some of its members of these ingredients so that they can do no more and must depart.

    Death, Legal and Illegal

  • Beria was more treacherous, more practiced in perfidy and cunning, more insolent and single-minded, than my father.

    Twenty Letters to a Father

  • But the major perfidy is American, since at various stages C.I.A. agents are working both with and against Uighur separatists, the Chinese government, Britons and one another.

    NYT > Home Page

  • Its videos praise fighters and rocket-launching teams; its broadcasts insult the Palestinian president, Mahmoud Abbas, for talking to Israel and the United States; its children’s programs praise “martyrdom,” teach what it calls the perfidy of the Jews and the need to end Israeli occupation over Palestinian land, meaning any part of the state of Israel. posted by GayandRight @ 10:37 AM

    The New York Times recognizes the venom of Hamas...

  • “Though I can still suffer when I recall her perfidy, I still laugh at her expression of entire conviction and sweet satisfaction that I must die, or at any rate sink into perpetual melancholy,” de Marsay went on.

    Another Study of a Woman


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  • an act of deliberate betrayal; a breach of a trust

    Sure, he was the best salesman in the company; but Michael had abused the trust of the firm, sharing product secrets with a competitor, and for such perfidy he was terminated.

    October 15, 2016

  • other means than his perfidy would have operated

    February 11, 2014