in·​fi·​del·​i·​ty ˌin-fə-ˈde-lə-tē How to pronounce infidelity (audio)
plural infidelities
: the act or fact of having a romantic or sexual relationship with someone other than one's husband, wife, or partner
: unfaithfulness to a moral obligation : disloyalty
: lack of belief in a religion

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 Prior to Stewart’s infidelity, the couple were seen cuddling at the Cannes Film Festival in May 2012 and had a date night in Hollywood in July 2012, just days before the actress’s public apology. Collette Reitz, Peoplemag, 15 Feb. 2024 This may include lying to one another, hiding financial information, engaging in infidelity, sharing private information with others without permission, emotional neglect, disregarding each other’s needs and more. Mark Travers, Forbes, 10 Feb. 2024 In real life, Paley's constant infidelity was an open secret. Cady Lang, TIME, 2 Feb. 2024 Tensions notably come to a head between Bennie and his sister-in-law Lucretia (a game Wanda Sykes) because of his past infidelity, which provides some of the sitcom's funniest moments via razor-sharp one-liner wars. Andrew Walsh,, 30 Jan. 2024 More broadly speaking, in our experience, financial missteps in relationships typically arise from poor communication, keeping secrets (what some call financial infidelity), control issues, blending budgets, and emotional assumptions about a partner’s motivations. Bruce Helmer and Peg Webb, Twin Cities, 3 Feb. 2024 Store manager Chris Gomez says the star attraction is the huge gold nugget – even larger than the diamond Kobe Bryant bought his wife after his infidelity – ensconced in a display case inside a vault. Sacramento Bee, 30 Jan. 2024 Problems with infidelity, alcohol and pornography are common in American society, and so are books about Christian marriages. Scott Fowler, Charlotte Observer, 30 Jan. 2024 The concept for the series came about in a 2020 TikTok posted by Mayan, which detailed how her dad’s infidelity affected her family. Sarah Title, Peoplemag, 24 Jan. 2024 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'infidelity.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


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

First Known Use

15th century, in the meaning defined at sense 2

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

Dictionary Entries Near infidelity

Cite this Entry

“Infidelity.” Dictionary, Merriam-Webster, Accessed 24 Feb. 2024.

Kids Definition


in·​fi·​del·​i·​ty ˌin-fə-ˈdel-ət-ē How to pronounce infidelity (audio)
plural infidelities
: lack of faith in a religion
: unfaithfulness especially to one's husband or wife

More from Merriam-Webster on infidelity

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