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perfidious

[per-fid-ee-uh s] /pərˈfɪd i əs/
adjective
1.
deliberately faithless; treacherous; deceitful:
a perfidious lover.
Origin of perfidious
1590-1600
First recorded in 1590-1600, perfidious is from the Latin word perfidiōsus faithless, dishonest. See perfidy, -ous
Related forms
perfidiously, adverb
perfidiousness, noun
unperfidious, adjective
unperfidiously, adverb
unperfidiousness, noun
Synonyms
false, disloyal; unfaithful, traitorous.
Antonyms
faithful.
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Based on the Random House Dictionary, © Random House, Inc. 2017.
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British Dictionary definitions for perfidious

perfidious

/pəˈfɪdɪəs/
adjective
1.
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
adj.

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

Online Etymology Dictionary, © 2010 Douglas Harper
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