9 Grammatical Pitfalls


[per-fid-ee-uh s] /pərˈfɪd i əs/
deliberately faithless; treacherous; deceitful:
a perfidious lover.
Origin of perfidious
1590-1600; < Latin perfidiōsus faithless, dishonest. See perfidy, -ous
Related forms
perfidiously, adverb
perfidiousness, noun
unperfidious, adjective
unperfidiously, adverb
unperfidiousness, noun
false, disloyal; unfaithful, traitorous.
faithful. Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for perfidious
  • They utilize their blemishes with perfidious skill.
  • He dances energetically and has a wonderful time and he is completely unaware that his perfidious conduct has been revealed.
  • But any breakdown or inconvenience will quickly lead to condemnation of the management as both incompetent and perfidious.
  • This princess was not less cruel than haughty, nor less perfidious than impious.
  • Of course Lucia does go to the bridge game, just to see her perfidious strategy work itself out.
  • The cries and entreaties of the perfidious Saracen moved her not.
  • There is nothing perfidious in this practice as long as it is kept within bounds.
British Dictionary definitions for perfidious


guilty, treacherous, or faithless; deceitful
Derived Forms
perfidiously, adverb
perfidiousness, noun
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
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Word Origin and History for perfidious

1590s, from Latin perfidiosus "treacherous," from perfidia (see perfidy). Related: Perfidiously; perfidiousness.

Online Etymology Dictionary, © 2010 Douglas Harper
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