- deliberately faithless; treacherous; deceitful: a perfidious lover.
Origin of perfidious
SynonymsSee more synonyms for perfidious on Thesaurus.com
false, disloyal; unfaithful, traitorous.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for perfidiously
Taking advantage of his absence, they perfidiously vilified him to the king.
(Perfidiously to the Marchioness) Look out, you know he's becoming dangerous for you.Three Plays
Perfidiously, they only sought time to regain their strength.
He had been perfidiously treated, and Albuquerque now, in 1511, appeared before the city to call the monarch to account.Ocean's Story; or Triumphs of Thirty Centuries
This man entered into a conspiracy with the English, to betray to them the King to whom he had perfidiously sworn allegiance.Joseph Bonaparte
John S. C. Abbott
- 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
Word Origin and History for perfidiously
1590s, from Latin perfidiosus "treacherous," from perfidia (see perfidy). Related: Perfidiously; perfidiousness.
Online Etymology Dictionary, © 2010 Douglas Harper