What does perfidiousness mean?
Perfidiousness means the quality of being treacherous, disloyal, or faithless. It describes conduct that breaks a trust or conceals an intention to betray someone, often through deception. The word is formal and carries a strongly negative moral judgment, suggesting that the disloyalty is deliberate rather than accidental. It can refer to an individual’s character, but it is also commonly applied to actions, motives, alliances, or relationships: a government may condemn another country’s “perfidiousness,” while a novel may expose the “perfidiousness” of a trusted adviser. Although related to the adjective perfidious, perfidiousness is an abstract noun used to name the state or quality itself. Its Latin ancestry, through perfidia, connects it with ideas of treachery and broken faith, making it especially effective in discussions of political betrayal and concealed disloyalty.
nounThe quality or state of being perfidious; treachery, disloyalty, or faithlessness.
- The quality or state of being treacherous, disloyal, or deceptively faithless.
"The hidden alliance exposed the perfidiousness of the minister who had promised loyalty."
"Her colleagues were unable to explain the perfidiousness behind his sudden change of allegiance."
"The novel portrays the perfidiousness of a ruler who uses kindness as a disguise for cruelty."
The plural is grammatically possible but uncommon, especially when the noun is used for an abstract quality.
"The play explores the different perfidiousnesses of those who compete for power."
Perfidiousness names the betrayal of trust: it derives from a Latin word meaning treachery or broken faith.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does perfidiousness come from?
Perfidiousness comes through the English adjective perfidious, which was borrowed from Latin perfidiosus, meaning treacherous or faithless. The Latin word was related to perfidia, meaning treachery or betrayal. English later formed the abstract noun perfidiousness from this adjective, preserving its strong sense of disloyalty and deliberate breach of trust.
How perfidiousness is actually used
Perfidiousness is a formal and strongly disapproving term. It is more commonly used in literary, political, or historical contexts than in everyday speech.