- Today's Word
Perfidious
per-FID-ee-us
Definition
(adjective) Deliberately untrustworthy and deceitful; guilty of betraying trust or breaking faith.
Example
The perfidious advisor had been leaking confidential strategy to competitors for years, all while accepting promotions and praise from the company he was quietly destroying.
Word Origin
Perfidious derives from the Latin perfidiosus, meaning “treacherous,” rooted in perfidia — “faithlessness” — built from per- (“through” or “away”) and fides (“faith” or “trust”). The same root fides gives us fidelity, confide, and fiduciary — making perfidious the dark twin of an entire family of words built on trust and loyalty. It entered English in the 16th century and has carried its sense of calculated, deliberate betrayal ever since.
Fun Fact
The phrase “Perfidious Albion” — referring to England’s alleged habit of diplomatic treachery — became one of history’s most enduring political insults. First popularized by French writer Augustin de Ximénès in 1793 during the revolutionary wars, the phrase spread across Europe as a shorthand for British foreign policy that smiled warmly while pursuing its own interests at everyone else’s expense. Napoleon used it enthusiastically, and it remained a standard piece of anti-British rhetoric for over a century — proof that a single well-chosen adjective, applied with enough conviction, can define a nation’s reputation for generations.