infidelity
Americannoun
plural
infidelities-
marital disloyalty; adultery.
-
unfaithfulness; disloyalty.
-
lack of religious faith, especially Christian faith.
-
a breach of trust or a disloyal act; transgression.
noun
-
lack of faith or constancy, esp sexual faithfulness
-
lack of religious faith; disbelief
-
an act or instance of disloyalty
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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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.
Divorce lawyers say that what’s known as financial secrecy or infidelity is at the center of many splits.
From The Wall Street Journal • Apr. 19, 2026
Samantha Perkins, 36, a TikTok creator who posts about her own experience with financial infidelity, said she found “Strangers” relatable “for anyone who’s been through any kind of relational betrayal.”
From The Wall Street Journal • Apr. 17, 2026
Financial infidelity is at least as damaging to a marriage and a couple’s livelihood as other kinds of secrecy and unfaithfulness.
From MarketWatch • Mar. 2, 2026
Then came a different kind of cheating when medal-winning Norwegian biathlete Sturla Holm Laegreid confessed to infidelity in a TV interview.
From Los Angeles Times • Feb. 17, 2026
This was no fine-spirited gesture to clear the record: He charged Lovering with infidelity, a ruinous accusation.
From "The Devil in the White City" by Erik Larson
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.
