perfidious
per-FID-ee-uss
/pərˈfɪd.i.əs/
Deceitful and untrustworthy; guilty of breaking faith or violating a solemn oath.
Emphasizes the violation of trust, allegiance, or a sacred oath.
The story behind the word. In ancient Rome, Fides was the personified goddess of trust and solemn oaths. Adding the prefix per- transformed the word to mean going 'beyond' or 'through' faith—stepping right through your promises and shattering them. To be perfidious was to destroy the bond holding society together.
Word relationships
- treacherous: Treacherous implies hidden physical or moral danger, while perfidious specifically focuses on violating a solemn trust or oath.
- disloyal: Disloyal is a general term, whereas perfidious carries a dramatic moral condemnation.
- faithful: Faithful implies steadfast allegiance to vows or duties.
- loyal: Loyal stresses firm allegiance to a sovereign, friend, or cause.
Commonly confused with
- perfunctory: Perfunctory means done routinely without enthusiasm, while perfidious means deceitful and oath-breaking.
Word family
- perfidy (noun): Deceitfulness; untrustworthiness or breach of faith.
- perfidiously (adverb): In a perfidious or faith-breaking manner.
Collocations
- perfidious act
- perfidious ally
- perfidious betrayal
Idioms & expressions
- stab in the back
- bite the hand that feeds you
Example sentences
- "The foreign minister was condemned for his perfidious breach of the non-aggression treaty." Diplomatic history
Memory hook
PERFECT FAITH broken into pieces: PER-FID-ious destroying FIDes (faith). Breaker of sacred faith.
When not to use
Do not use for minor untruths; reserved for severe breaches of trust.
Fun facts
- 'Perfidious Albion' was a famous phrase used in France for centuries to describe Great Britain's shifting diplomatic alliances.
Related words
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