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
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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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Sturla Holm Lægreid’s spectacular on-air confession of infidelity didn’t win him any points with his ex-girlfriend.—
James Hibberd,
HollywoodReporter,
11 Feb. 2026
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Lægreid, who previously won gold in the relay at the Beijing Olympics in 2022 and has 14 world championship medals to his name, explained on Tuesday that he was prompted to address the breakup and infidelity publicly in the hopes of reconciliation.—
Shania Russell,
Entertainment Weekly,
11 Feb. 2026
Noun
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It’s filled with super-heightened emotions; unrestrained passion, betrayal, evil and even a magic spell or two.—
David Lyman,
Cincinnati Enquirer,
5 Feb. 2026
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What’s most striking about the response is the sense of betrayal about Aronofsky’s involvement.—
Jake Kanter,
Deadline,
5 Feb. 2026
Noun
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Advertisement Both Paxton’s baggage and his history of using his office to troll Democrats is a central feature in the Republican primary, which has devolved into a barrage of personal attacks of betrayal, adultery, and corruption.—
Philip Elliott,
Time,
10 Feb. 2026
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Ken Paxton, a Republican running for the Senate, denied the adultery allegations.—
Jane Harper,
Dallas Morning News,
15 Jan. 2026
Noun
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Perfidy — from the French perfidie via the Latin perfidia — means deceitfulness, treachery or a breach of faith or promise.—
Harmeet Kaur,
CNN Money,
21 Jan. 2026
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But despite all this, not every Chelsea fan outside his family will regard this transfer as treachery.—
Simon Johnson,
New York Times,
17 Jan. 2026
Noun
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British police raided two properties linked to Mandelson on Friday as part of an investigation into misconduct in public office.—
Billy Stockwell,
CNN Money,
9 Feb. 2026
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The Proctor case could prove a test of Hochman’s commitment to prosecuting police misconduct cases.—
Richard Winton,
Los Angeles Times,
9 Feb. 2026
Noun
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Until now, the idea that the secretary of defense would accuse a lawmaker of treason simply for disagreeing with him would be laughable.—
Missy Ryan,
The Atlantic,
9 Feb. 2026
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Saudi Arabi accused the UAE of supporting the separatists, and smuggling the STC leader, Aidarous al-Zubaidi, who is wanted for treason, out of Yemen and flying him to Abu Dhabi.—
Arkansas Online,
Arkansas Online,
8 Feb. 2026
Noun
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An honor council, comprised of administrators, teachers, and members of the student government, would sit in judgment on cases of alleged cheating.—
Nell Freudenberger,
Harpers Magazine,
27 Jan. 2026
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In the wake of the cheating, FIS has modified its rules and brought in a coordinator to oversee screening of gear and hired former Austrian ski jumper Mathias Hafele to work as equipment expert.—
Brian Melley,
Chicago Tribune,
23 Jan. 2026
Cite this Entry
“Unfaithfulness.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/unfaithfulness. Accessed 17 Feb. 2026.
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