- deliberately faithless; treacherous; deceitful: a perfidious lover.
Origin of perfidious
Synonyms for perfidiousSee more synonyms for on Thesaurus.com
Antonyms for perfidious
Related Words for perfidiouslymaliciously, unscrupulously, deceitfully, perfidiously, cruelly, viciously, ruthlessly, unconscionably, unethically, treacherously, basely, crookedly, malevolently, roguishly
Examples from the Web for perfidiously
Historical Examples of 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
1590s, from Latin perfidiosus "treacherous," from perfidia (see perfidy). Related: Perfidiously; perfidiousness.