1
as in infidelity
lack of faithfulness especially to one's husband or wife
he eventually forgave his wife's unfaithfulness
Synonyms & Similar Words
Relevance
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
Examples are automatically compiled from online sources to
show current usage.
Read More
Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
Send us feedback.
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
-
Their royal union was complicated by infidelity and intense media scrutiny.—
Bailey Bujnosek,
InStyle,
25 Feb. 2026
-
Cornyn has defended the bipartisan gun law, has chided Hunt over missing votes in Washington and relentlessly trolled Paxton over his divorce, allegations of infidelity and issues surrounding his impeachment.—
Gromer Jeffers Jr,
Dallas Morning News,
23 Feb. 2026
Noun
-
Even with the game result finalized at this point, the anticipation to see how Maura would react to Rob’s betrayal was almost sky high, and the result matched the moment.—
Dalton Ross,
Entertainment Weekly,
27 Feb. 2026
-
Key leaders in the MAHA movement regarded the move as a betrayal.—
Tom Bartlett,
The Atlantic,
26 Feb. 2026
Noun
-
The Texas attorney general beat a 2023 impeachment trial on corruption charges and reached a deal to end a long-running securities fraud case but now faces a contentious divorce over allegations of adultery.—
Meg Kinnard,
Chicago Tribune,
17 Feb. 2026
-
Its roots are in publicly paying penance for serious sins or crimes in the eyes of the church, like adultery or apostasy, which means renouncing the church and its beliefs.—
Lianna Norman,
Florida Times-Union,
16 Feb. 2026
Noun
-
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
-
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
-
The session was the latest in a series of forums the Democratic lawmakers have held to highlight DHS misconduct.—
Michael Loria,
USA Today,
24 Feb. 2026
-
Attia's departure came to light on the same day that police in London arrested Britain's former ambassador to the United States, Peter Mandelson, on suspicion of misconduct in public office.—
Dan Mangan,
CNBC,
23 Feb. 2026
Noun
-
Fearful of being captured and charged with treason for opposing British rule, American leaders would gather in private homes or taverns.—
Phaedra Trethan,
USA Today,
23 Feb. 2026
-
In France in the late nineteenth century, a Jewish Army captain, Alfred Dreyfus, was put on trial on false charges of treason.—
Nicholas Lemann,
New Yorker,
21 Feb. 2026
Noun
-
That cheating is rampant in our elections.—
TIME Staff,
Time,
25 Feb. 2026
-
Not every young person feels this type of cheating is wrong.—
Eva Roytburg,
Fortune,
24 Feb. 2026
Cite this Entry
“Unfaithfulness.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/unfaithfulness. Accessed 1 Mar. 2026.
Copy CitationLove words? Need even more definitions?
Merriam-Webster unabridged
