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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However, the relationship remained volatile, and rumors of infidelity persisted.—
Meredith Kile,
PEOPLE,
1 May 2026
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The Grammy winner, 31, who debuted late last month as Zidler in the Tony-winning adaptation of the 2001 musical film, will now be taking her final bow on Friday — less than a week after her post Saturday accusing 36-year-old Thompson of infidelity.—
Jami Ganz,
New York Daily News,
28 Apr. 2026
Noun
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Our Extraordinary Summer by Lori Wilde Estranged sisters Calista and Athena Dempsey are forced to reunite on Hobby Island after their mother’s death, confronting old betrayals and unhealed wounds.—
Kait Hanson,
Southern Living,
2 May 2026
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Andrew Spar, president of the Florida Education Association, an umbrella organization for the local unions, quickly criticized the bill as a betrayal of working-class Floridians.—
Jeffrey S. Solochek,
Miami Herald,
1 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 committee has established a special investigative subcommittee to examine whether Mills engaged in conduct that could include improper relationships, financial misconduct, or abuse of his official position.—
Nik Popli,
Time,
11 May 2026
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In the months that followed, former students began filing lawsuits alleging abuse and misconduct at the program.—
Rachel Hale,
USA Today,
11 May 2026
Noun
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She had been imprisoned for more than a year on charges of treason stemming from a $52 donation to a charity aiding Ukraine.—
Christopher Cann,
USA Today,
10 May 2026
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These laws required individuals accused of treason to appear in court and defend themselves.—
Kimberly Nath,
The Conversation,
7 May 2026
Noun
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But, Keoghan said, the masses primarily only saw the first video, which fueled the widespread cheating rumors about him.—
Rachel Raposas,
PEOPLE,
28 Apr. 2026
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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
Cite this Entry
“Unfaithfulness.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/unfaithfulness. Accessed 12 May. 2026.
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