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. noun
    an act of deliberate betrayal
    synonyms: betrayal, treachery, treason
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    double cross, double-crossing
    an act of betrayal
    an act of betrayal
    type of:
    dishonesty, knavery
    lack of honesty; acts of lying or cheating or stealing
  2. noun
    betrayal of a trust
    synonyms: perfidiousness, treachery
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    the quality of being designed to entrap
    type of:
    the quality of being disloyal
Word Family