1
as in infidelity
lack of faithfulness especially to one's husband or wife
he eventually forgave his wife's unfaithfulness
Synonyms & Similar Words
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Antonyms & Near Antonyms
2
as in betrayal
the act or fact of violating the trust or confidence of another
the jaw-dropping unfaithfulness of the person she had considered her best friend was deeply hurtful
Synonyms & Similar Words
Antonyms & Near Antonyms
3
as in adultery
a sexual encounter or relationship between a married person and someone other than their spouse
there were charges of unfaithfulness on both sides
Synonyms & Similar Words
Antonyms & Near Antonyms
Example Sentences
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Recent Examples of unfaithfulness
According to The Daily Mail, unfaithfulness might have been the cause.
—
Lizzie Lanuza, StyleCaster, 12 Jan. 2026
Harbour also recently made headlines following the release of estranged wife Lily Allen's latest album, West End Girl, which contained references many interpreted as pointing toward alleged unfaithfulness on Harbour's part, though the actor isn't explicitly named in the lyrics.
—Joey Nolfi, Entertainment Weekly, 7 Nov. 2025
Milvia Marigliano is a hoot as Coco Vulori, an old dear friend with some very loud opinions to express, and maybe the key to helping DeSantis solve his wife’s onetime unfaithfulness.
—Pete Hammond, Deadline, 27 Aug. 2025
Lizzie Lanuza, StyleCaster, 12 Jan. 2026
Harbour also recently made headlines following the release of estranged wife Lily Allen's latest album, West End Girl, which contained references many interpreted as pointing toward alleged unfaithfulness on Harbour's part, though the actor isn't explicitly named in the lyrics.
—Joey Nolfi, Entertainment Weekly, 7 Nov. 2025
Milvia Marigliano is a hoot as Coco Vulori, an old dear friend with some very loud opinions to express, and maybe the key to helping DeSantis solve his wife’s onetime unfaithfulness.
—Pete Hammond, Deadline, 27 Aug. 2025
Recent Examples of Synonyms for unfaithfulness
Noun
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In later years, Lynn described her husband as supportive of her work but also difficult in their personal life, acknowledging struggles that included infidelity and physical abuse.—
Virginia Chamlee,
PEOPLE,
14 Apr. 2026
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In more ways than one, Clark and Carol weren’t alone in their infidelity.—
Alison Herman,
Variety,
13 Apr. 2026
Noun
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SoulCycle, Flywheel, Peloton — the billion-dollar boutique fitness revolution built on ambition, betrayal and toxic sweat.—
Ryan Lattanzio,
IndieWire,
16 Apr. 2026
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To do so—and this book is my attempt—would not, could not constitute a betrayal.—
Literary Hub,
Literary Hub,
15 Apr. 2026
Noun
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The Bible teaches that lying, stealing, adultery and coveting your neighbor’s property are sins.—
Sun Sentinel Editorial Board,
Sun Sentinel,
16 Mar. 2026
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The facile novelty of adultery is its own mask, a sexy way of dressing up a deep, frightened longing for security.—
Sara Holdren,
Vulture,
6 Mar. 2026
Noun
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Inflamed by Ratansen’s adviser’s account of Padmavati’s beauty, Alauddin Khalji storms the fortress by treachery rather than valor.—
Encyclopedia Britannica,
Encyclopedia Britannica,
9 Apr. 2026
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But Bateman's treachery also had a distinctly silly side.—
Ryan Coleman,
Entertainment Weekly,
8 Apr. 2026
Noun
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British police launched a criminal probe and arrested Mandelson in February on suspicion of misconduct in public office.—
Jill Lawless,
Los Angeles Times,
20 Apr. 2026
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Labor Secretary Lori Chavez-DeRemer is leaving her post amid an internal investigation brought on by complaints about misconduct by the secretary while in office.—
Andrea Hsu,
NPR,
20 Apr. 2026
Noun
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Russia’s Federal Security Service detained a former freelance journalist for Radio Free Europe/Radio Liberty in eastern Siberia on charges of treason.—
Bloomberg News,
Bloomberg,
9 Apr. 2026
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Consider this evilmeister’s brazen acts of treason and revenge, unbounded deceit, swinish immorality and negative role modeling.—
Voice of the People,
New York Daily News,
5 Apr. 2026
Noun
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But even for in-person classes, adaptations to prevent LLM cheating are often concessions that reduce pedagogical quality.—
ArsTechnica,
ArsTechnica,
13 Apr. 2026
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Time and again, the panel of experts invited to provide testimony said voter fraud is exceedingly rare and that there is no evidence of widespread cheating.—
Linh Tat,
Daily News,
8 Apr. 2026
Cite this Entry
“Unfaithfulness.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/unfaithfulness. Accessed 21 Apr. 2026.
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