perfidiously
In faithless manner
Perfidiously means in a treacherous or deceitful manner, through deliberate betrayal of trust: He perfidiously sold state secrets to the enemy.
The word carries a formal, literary tone and implies not just dishonesty but a violation of faith or loyalty—someone acting perfidiously has broken a bond they were expected to honor.
Deliberate violation of trust
- backstabBetray someone's trust
- double-crossTreacherous deception of partner
- turncoatOne who betrays allegiance
- JudasArchetypal betrayer name
betrayer · treason · disloyalty · defection · quisling · sellout · renegade · apostasy
Untrustworthy, lacking loyalty
- falseNot matching reality
- disloyalUntrue to commitments
- unreliableNot consistently performing
- unscrupulousLacking moral principles
unprincipled · inconstant · fickle · undependable · shady · slippery · Janus-faced · hollow-hearted
Deliberate misleading behavior
- guileSly, strategic dishonesty
- schemingCrafty and calculating
- subterfugeDeliberate deception to conceal
- chicaneryDeception through clever manipulation
artifice · cunning · deception · mislead · manipulation · conniving · insidious · machination
treachery
Deliberate violation of trust
- backstabBetray someone's trust
- double-crossTreacherous deception of partner
- turncoatOne who betrays allegiance
Judas · betrayer · treason · disloyalty · defection · quisling · sellout · renegade · apostasy · sedition
faithless
Untrustworthy, lacking loyalty
- falseNot matching reality
- disloyalUntrue to commitments
- unreliableNot consistently performing
unscrupulous · unprincipled · inconstant · fickle · undependable · shady · slippery · Janus-faced · hollow-hearted · fair-weather
duplicity
Deliberate misleading behavior
- guileSly, strategic dishonesty
- schemingCrafty and calculating
- subterfugeDeliberate deception to conceal
chicanery · artifice · cunning · deception · mislead · manipulation · conniving · insidious · machination · plotting
perfidiouslyfaithfully
With unwavering loyalty
loyally · devotedly · dependably · steadfastly · reliably
perfidiouslyhonestly
In a truthful manner
honorably · sincerely · truthfully · uprightly · virtuously