What does perfidy mean?
Perfidy is a formal noun meaning betrayal of trust, loyalty, or a solemn promise, particularly conduct that is deliberately disloyal or treacherous. It is often used when describing diplomacy, warfare, political allegiance, or personal relationships in which one party is thought to have violated good faith. Unlike the broad word “betrayal,” perfidy carries a distinctly accusatory and elevated tone, suggesting not merely failure of loyalty but intentional treachery. The related adjective “perfidious” is often applied to a person, action, or motive, while “perfidiously” describes the manner of such betrayal. Although the word can apply to personal relationships, it has a strongly literary and historical flavour and is especially effective in discussions of public honour, allegiance, and deception.
nounBetrayal of trust or loyalty; treachery. The word characteristically refers to a deliberate breach of faith, especially in political, military, or personal relationships.
- Betrayal of trust or loyalty, especially deliberate and disloyal conduct.
"The diplomat was accused of perfidy after disclosing confidential negotiations to the enemy."
"She discovered the perfidy behind the apparent offer of friendship."
"The account of the coup emphasized the perfidy of those who had sworn allegiance to the government."
The plural is used for individual acts or instances of betrayal or treachery.
"The witnesses described years of perfidies that had made cooperation impossible."
Perfidy literally describes faithlessness: it comes from a Latin word meaning “faithless” or “treacherous.”
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does perfidy come from?
The word entered Middle English from Old French perfidie, which was borrowed from Latin perfidia, meaning “faithlessness” or “treachery.” Latin perfidia was derived from perfidus, “faithless” or “deceitful,” a word related to fides, “faith” or “trust.” The word has long conveyed the betrayal of an obligation or pledge, which explains its enduring association with treachery and divided loyalty.
Related word forms
How perfidy is actually used
A formal, literary, and somewhat old-fashioned term. It is stronger and more accusatory than “betrayal” and is especially associated with political treachery, divided loyalties, and violations of trust.