in·​fi·​del·​i·​ty | \ˌin-fə-ˈde-lə-tē, -(ˌ)fī-\
plural infidelities

Definition of infidelity 

1a : the act or fact of having a romantic or sexual relationship with someone other than one's husband, wife, or partner

b : unfaithfulness to a moral obligation : disloyalty

2 : lack of belief in a religion

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Examples of infidelity in a Sentence

She was convinced that her husband was guilty of infidelity. He has admitted to a number of marital infidelities.

Recent Examples on the Web

She was devastated by her parents’ divorce, by the infidelities that drove them apart. Gary Thompson,, "'Whitney': A moving, revealing look at the life of Whitney Houston," 4 July 2018 The plot may sound like the setup for a schmaltzy rom com, but Catastrophe approaches everything from alcoholism and infidelity to motherhood with uproarious frankness. Justine Harman, Glamour, "Sharon Horgan Is the Realest Mother on TV," 4 July 2018 On this date, the anti-infidelity anthem began its seven-week rule. Gary Trust, Billboard, "This Week in Billboard Chart History: In 2008, Katy Perry 'Kissed a Girl' & Hit No. 1 on the Hot 100," 2 July 2018 Breaks or forks in the heart line can suggest multiple lovers, transformative bonds, or even infidelity. Aliza Kelly Faragher, Allure, "A Beginner's Guide to Reading Palms," 4 June 2018 Cheating husbands and wives might be most common in Seattle, according to a report from infidelity website Ashley Madison. Ashley May, USA TODAY, "Husband cheating? Ashley Madison says member signups spiked in these cities last year," 22 June 2018 The outings come as a surprise for some fans after news of Tristan's alleged infidelity broke just days before Khloé gave birth to the couple's daughter, True Thompson. Kayleigh Roberts, Marie Claire, "Khloé Kardashian Was Spotted Cheering for Tristan Thompson at a Game in Cleveland," 6 May 2018 Then, after telling his wife about his infidelity, Ken asked Samantha to join them in a threesome. Kelly Conaboy, The Cut, "Sex and the City," 6 June 2018 Rumors of Prince Charles’s infidelity were widespread, and the pair divorced in 1996. Vogue, "The 20 Most Memorable Royal Weddings of All Time," 11 May 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'infidelity.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of infidelity

15th century, in the meaning defined at sense 2

History and Etymology for infidelity

Middle English infidelite, borrowed from Middle French infidelité, borrowed from Latin infidēlitāt-, infidēlitās "faithlessness, inconstancy," from infidēlis "unfaithful, disloyal" + -itāt-, -itās -ity — more at infidel entry 2

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Last Updated

5 Nov 2018

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Time Traveler for infidelity

The first known use of infidelity was in the 15th century

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playful or foolish behavior

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