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perfidious

American  
[per-fid-ee-uhs] / pərˈfɪd i əs /

adjective

  1. deliberately faithless; treacherous; deceitful.

    a perfidious lover.

    Synonyms:
    traitorous, unfaithful, disloyal, false
    Antonyms:
    faithful

perfidious British  
/ pəˈfɪdɪəs /

adjective

  1. guilty, treacherous, or faithless; deceitful

"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

Other Word Forms

Etymology

Origin of perfidious

First recorded in 1530–40; from Latin perfidiōsus “faithless, dishonest”; cf. perfidy, -ous

Explanation

If someone accuses you of being perfidious, you should probably be offended — it means underhanded, treacherous, deceitful — even evil. If you betray people often, you're perfidious: traitors are extremely perfidious. Besides betrayal, this word implies lying and maybe other kinds of awful behavior, like stealing and taking bribes. Everyone tries to avoid perfidious people. Perfidious is kind of an old-fashioned word, but being perfidious will never go out of style, unfortunately.

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Vocabulary lists containing perfidious

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.

Malodorous, Nefarious, Obstreperous, Perfidious -- I could go on all day.

From Washington Post • Aug. 2, 2018

Perfidious in their own nature, thev suspected the sincerity of the admiral; and conscious of the extent of their offences, doubted his having the magnanimity to pardon them.

From The Life and Voyages of Christopher Columbus (Volume II) by Irving, Washington

Cosmus, Duke of Florence, had a Desperate Saying against Perfidious or Neglecting Friends, as if these wrongs were unpardonable.

From At a Winter's Fire by Capes, Bernard Edward Joseph

To many Frenchmen "Perfidious Albion" was, far more than Germany, the secular foe.

From A History of the Third French Republic by Wright, C. H. C. (Charles Henry Conrad)

Forgetting the facts of history, we often smile at the grumblings of the Continental nations anent "Perfidious Albion" and "British gold."

From The History of the United States from 1492 to 1910, Volume 1 From Discovery of America October 12, 1492 to Battle of Lexington April 19, 1775 by Hawthorne, Julian

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