perfidious
adjective | /perfidious/
Advanced WordsHARD
tending to betray; deceitful and untrustworthy
perfidious
adjective | /perfidious/
Advanced WordsHARDtending to betray; deceitful and untrustworthy
Learning Progress
Synonyms
treacherousdeceitfuldisloyalfaithless
Antonyms
faithfulloyaltrustworthy
Examples
"The spy's perfidious actions were exposed by leaked documents."
"He felt betrayed by a perfidious friend who revealed secrets."
Mnemonic Trick
PERFIDIOUS → PER (through) + FID (faith) — breaking faith, treacherous.
Etymology
From Latin perfidia “treachery.”
Used for betrayal or deceit of trust.
Source: Advanced WordsAdded: 9/28/2025
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