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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During her weekslong trial, friends of Richinses described how the couple had moments of material strife and struggled with infidelity.—
Minyvonne Burke,
NBC news,
13 May 2026
-
Three years after leaving, Fulmer broke his silence on the infidelity scandal that torpedoed his career in an exclusive interview with PEOPLE.—
Zoey Lyttle,
PEOPLE,
12 May 2026
Noun
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But somewhere along the way, a portion of the WNBA ecosystem — fans, players and even some media members — started treating criticism as betrayal.—
Amber Harding OutKick,
FOXNews.com,
14 May 2026
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The sequel series is based on similar – and familiar – concepts of love, loyalty and betrayal, once again set in the mafia underworld.—
Jesse Whittock,
Deadline,
14 May 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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Upon learning of Ava’s treachery, Deborah HOWLS.—
Jessica M. Goldstein,
Vulture,
1 May 2026
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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
Noun
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The timeline of the Andrew scandal has been heavily discussed, even before the disgraced former prince was arrested for suspicion of misconduct in public office.—
Lizzie Lanuza,
StyleCaster,
17 May 2026
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In December, Hill pleaded guilty to state charges of misconduct, perjury and obstruction of justice and was put on probation.—
N'dea Yancey-Bragg,
USA Today,
15 May 2026
Noun
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Tried and convicted for misprision of treason, she was locked away in her bedroom in the palace for eight months.—
Kathleen Wong,
USA Today,
18 May 2026
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Even so, the rumors of treason ground on.—
Thomas Mallon,
New Yorker,
18 May 2026
Noun
-
Nah, my dreams of us are probably better anyway - cheating?—
Sean Joseph OutKick,
FOXNews.com,
14 May 2026
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And according to the data, most of this cheating is done with generative AI.—
Nate Anderson,
ArsTechnica,
13 May 2026
Cite this Entry
“Unfaithfulness.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/unfaithfulness. Accessed 19 May. 2026.
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