See perfidy in Webster's New World Roget's A-Z Thesaurus II
noun
Betrayal, especially of a moral obligation:
disloyalty, faithlessness, false-heartedness, falseness, falsity, infidelity, perfidiousness, traitorousness, treacherousness, treachery, unfaithfulness. See continue, trustWillful betrayal of fidelity, confidence, or trust:
treacherousness, treachery, treason. See trust
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