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 December, Kristy alleged infidelity as the reason for her split from Desmond, per court records previously obtained by PEOPLE.—
Zoey Lyttle,
PEOPLE,
29 Jan. 2026
-
One couple will discover infidelity.—
Marta Balaga,
Variety,
29 Jan. 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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Ken Paxton, a Republican running for the Senate, denied the adultery allegations.—
Jane Harper,
Dallas Morning News,
15 Jan. 2026
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The book presents itself as a comic take on the classic adultery novel and a send-up of a narrow, self-conscious group of downwardly mobile New Yorkers.—
Literary Hub,
Literary Hub,
8 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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Blind spots, poor image quality, and limited video retention undermine investigations and allow misconduct to go undetected or unprosecuted.—
Walter Pavlo,
Forbes.com,
27 Jan. 2026
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Progressives also have endorsed the reversal of qualified immunity protections, which shield agents from misconduct lawsuits.—
Ana Ceballos,
Los Angeles Times,
26 Jan. 2026
Noun
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The president’s team moved quickly to prosecute the sheriff for treason.—
Michael Scherer,
The Atlantic,
22 Jan. 2026
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Veteran opposition figure Kizza Besigye, a four-time presidential candidate, remains in prison after he was charged with treason last February.—
Los Angeles Times,
Los Angeles Times,
17 Jan. 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 8 Feb. 2026.
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