perfidiousness
Quality of faithlessness
Perfidiousness is the quality of being treacherous or deceitful—a deliberate betrayal of trust.
The word carries a formal, almost literary weight, suggesting not casual dishonesty but calculated disloyalty: The perfidiousness of his closest advisor shocked the king.
It implies a breach of faith where loyalty was expected or promised.
Deliberate violation of trust
- backstabbingCovert betrayal of trust
- double-crossTreacherous deception of partner
- treasonBetraying one's nation
- disloyaltyBreach of allegiance
defection · sedition · apostasy · reneging · turncoat · Judas · quisling · betrayer
Deliberate misleading behavior
- guileSly, strategic dishonesty
- subterfugeDeliberate deception to conceal
- chicaneryDeception through clever manipulation
- deceptionIntentional misleading of others
artifice · fraudulence · dissembling · cunning · trickery · slyness · hoodwinking · two-faced
Not consistently performing
- undependableNot consistently trustworthy
- untrustworthyNot deserving of confidence
- faithlessUntrustworthy, lacking loyalty
- disloyalUntrue to commitments
false · shifty · slippery · snake · snaky · treasonous · dishonorable · unscrupulous
Prone to fluctuation
- changeableCapable of alteration
- capriciousSubject to sudden changes
- mercurialProne to sudden change
- fickleErratically disloyal in affection
wavering · vacillating · false-hearted · fair-weather · disloyal · unfaithful · flighty · erratic
treachery
Deliberate violation of trust
- backstabbingCovert betrayal of trust
- double-crossTreacherous deception of partner
- treasonBetraying one's nation
disloyalty · defection · sedition · apostasy · reneging · turncoat · Judas · quisling · betrayer · sabotage
duplicity
Deliberate misleading behavior
- guileSly, strategic dishonesty
- subterfugeDeliberate deception to conceal
- chicaneryDeception through clever manipulation
deception · artifice · fraudulence · dissembling · cunning · trickery · slyness · hoodwinking · two-faced · mendacity
unreliable
Not consistently performing
- undependableNot consistently trustworthy
- untrustworthyNot deserving of confidence
- faithlessUntrustworthy, lacking loyalty
disloyal · false · shifty · slippery · snake · snaky · treasonous · dishonorable · unscrupulous · crooked
inconstant
Prone to fluctuation
- changeableCapable of alteration
- capriciousSubject to sudden changes
- mercurialProne to sudden change
fickle · wavering · vacillating · false-hearted · fair-weather · disloyal · unfaithful · flighty · erratic · unreliable
perfidiousnessloyalty
Faithful commitment to another
faithfulness · fidelity · trustworthiness · allegiance · fealty
confidence, fidelity, bona fide, confide, diffident, perfidy, affidavit, perfidious, infidel