perfidious
Americanadjective
adjective
Other Word Forms
- perfidiously adverb
- perfidiousness noun
- unperfidious adjective
- unperfidiously adverb
- unperfidiousness noun
Etymology
Origin of perfidious
First recorded in 1530–40; from Latin perfidiōsus “faithless, dishonest”; perfidy, -ous
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Samuel Pepys knew him; the British diarist thought him “a perfidious rogue.”
From The Wall Street Journal • Mar. 11, 2026
The head of one of them, who preferred to remain anonymous, described it as a "perfidious and effective" strategy.
From Barron's • Nov. 1, 2025
“If the initial findings are confirmed, it will be a perfidious attack on our electricity infrastructure,” Stübgen said.
From Seattle Times • Mar. 5, 2024
Nick Davis grew up with the Mankiewicz legend: great Herman and perfidious Joe.
From Los Angeles Times • May 17, 2022
“Behold, campers, this vile and destructive creature! This killer of songbirds! This murderer of chipmunks! This perfidious predator!”
From "Klawde: Evil Alien Warlord Cat" by Johnny Marciano and Emily Chenoweth
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
