infidelity
Americannoun
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marital disloyalty; adultery.
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unfaithfulness; disloyalty.
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lack of religious faith, especially Christian faith.
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a breach of trust or a disloyal act; transgression.
noun
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lack of faith or constancy, esp sexual faithfulness
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lack of religious faith; disbelief
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an act or instance of disloyalty
Other Word Forms
Noun Inflected Forms
Etymology
Origin of infidelity
First recorded in 1375–1425; late Middle English, from Latin infidēlitās; equivalent to infidel + -ity
Explanation
Someone guilty of infidelity is cheating on a spouse or romantic partner. A common cause of divorce and heartbreak is infidelity. Fidel means "faithful" or "loyal." Tack on the prefix in, which means "not," and you've got yourself infidelity — the act of being unfaithful. The word can also be used to refer to someone's religious beliefs. Run angrily through a church and claim that God doesn't exist, and your fellow churchgoers will think you lack faith, or that you are guilty of infidelity.
Vocabulary lists containing infidelity
George Washington's Farewell Address (1796)
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The Woman Warrior
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
His wife, state Sen. Angela Paxton, is divorcing him on “biblical grounds,” accusing him of infidelity.
From Salon • Jun. 17, 2026
I didn’t want to make a show about a marriage that was on the rocks because of infidelity.
From Los Angeles Times • Jun. 1, 2026
The notebooks do allude to the depression of his wife, Francine Faure, occasioned by his serial infidelity.
From The Wall Street Journal • May 8, 2026
In the album, Allen leveled several shocking accusations about Harbour’s alleged infidelity, with the townhouse playing a central role in the record’s title track.
From MarketWatch • Apr. 22, 2026
He scrolled through paragraphs about rivalries, infidelity, and then...
From "Night Owls" by A.R. Vishny
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
