perfidious
adjective
Did you know?
We wouldn't lie to you about the history of "perfidious" - even though the word itself suggests deceitfulness. The modern English meaning of "perfidious" remains faithful to that of its Latin ancestor, perfidus, which means "faithless." English speakers have used "perfidious" to mean "treacherous" since at least 1572. One of the earliest known uses of the term can be found in Act V, scene iii of Shakespeare’s All's Well That Ends Well: the "perfidious slave" Parolles is thought to be an unreliable witness; he’ll say whatever suits his purpose, whether true or not. In contemporary usage, "perfidious" not only implies treacherousness, but an inability to be reliable or honorable.
Examples of perfidious in a Sentence
A.o. Scott, New York Times, 3 Feb. 2026
However, this question has now been resurrected and amplified by conservatives as evidence of a perfidious lack of patriotism.
—Charlie Campbell, Time, 2 Feb. 2026
Her Ashley is the movie’s fourth and fifth wheel, dismissed as both a perfidious troublemaker and a New Age airhead—a life coach in need of a wife coach.
—Justin Chang, New Yorker, 22 Aug. 2025
This perfidious situation, unintentional as its creation may have been, was strongly critiqued as far back as 1983 by Jonathan Crush and Paul Wellings in an article in The Journal of Modern African Studies.
—The Editors, JSTOR Daily, 15 Aug. 2025
See All Example Sentences for perfidious
Cite this Entry
“Perfidious.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/perfidious. Accessed 14 Feb. 2026.
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perfidious
adjective
