perfidy

If you shared your most embarrassing secrets with a friend who then told them to everyone he knows, his betrayal could be described as perfidy.

The noun perfidy means "deceitfulness" or "treachery," so it's not just being mean, but deliberately betraying a trust. The Latin root of perfidy is made up of per, or "through," and fidem, or "faith." So in order for perfidy to happen, there has to have first been a sense of faith in place, which was then broken or betrayed.

Definitions of perfidy
1

n an act of deliberate betrayal

Synonyms:
betrayal, treachery, treason
Types:
double cross, double-crossing
an act of betrayal
sellout
an act of betrayal
Type of:
dishonesty, knavery
lack of honesty; acts of lying or cheating or stealing

n betrayal of a trust

Synonyms:
perfidiousness, treachery
Types:
insidiousness
the quality of being designed to entrap
Type of:
disloyalty
the quality of being disloyal

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