infidelity
[noun]
Synonyms: disloyalty, faithlessness, falseness, falsity, perfidiousness, perfidy, unfaithfulness

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Antonyms: fidelity
Contrasted words: devotion, faithfulness, fealty, constancy, loyalty, steadfastness
Related Idioms: bad faith
Related Words: fickleness, inconstancy, treacherousness, treachery, treason

[TahlilGaran] English Synonym Dictionary ▲

in‧fi‧del‧i‧ty /ˌɪnfəˈdeləti, ˌɪnfɪˈdeləti/ noun (plural infidelities) [uncountable and countable]
when someone has sex with a person who is not their wife, husband, or partner:
marital infidelity

[TahlilGaran] Dictionary of Contemporary English ▲