- Today's Word
Perfidious
[per-FID-ee-us]
Definition
- (adjective) Someone who is deceitful and untrustworthy, particularly someone who betrays trust or breaks their promises. It refers to behavior that is treacherous, disloyal, or faithless.
Example
The perfidious business partner secretly sold company secrets to competitors while pretending to be dedicated to the firm’s success.
Fun Fact
“Perfidious” comes from the Latin “perfidiosus,” derived from “perfidia” meaning “faithlessness” or “treachery.” The word breaks down into “per” (meaning “through” or “away from”) and “fides” (meaning “faith” or “trust”). This same Latin root “fides” gives us other words like “fidelity,” “confident,” and “fiduciary.” The term gained particular historical significance in the phrase “Perfidious Albion,” a pejorative term used by France and other European nations from the 13th century onward to describe what they saw as England’s tendency to be diplomatically unreliable or treacherous. During the medieval period, being perfidious was considered one of the most serious character flaws a noble could possess, as it violated the feudal code of honor and loyalty. Today, while less commonly used, it remains one of the strongest words in English for describing betrayal and untrustworthiness.
(adjective) Devoid of intelligence, substance, or meaningful content; empty in a way that is made worse by the appearance of fullness.
The panel discussion was so vacuous — four articulate people saying nothing of substance for ninety minutes — that the audience left feeling vaguely cheated by their own attention.
Vacuous derives from the Latin vacuus, meaning “empty” or “void,” rooted in vacare — “to be empty” or “to be free.” The same root gives us vacuum, vacant, vacation — all words built around the idea of emptiness or absence. It entered English in the 17th century, initially used in scientific contexts to describe a literal vacuum before acquiring its cutting figurative sense of a mind or expression that contains nothing worth engaging with.