infidelity

noun

in·​fi·​del·​i·​ty ˌin-fə-ˈde-lə-tē 

-(ˌ)fī-

plural infidelities

1

a

: 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

Synonyms

• disloyalty
• faithlessness
• falseness
• falsity
• inconstancy
• perfidiousness
• perfidy
• unfaithfulness

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

Denver jurors are expected to hear this summer about the many allegations of infidelity, coercion, scheming and fraud that have divided one of the city’s most prominent families. —Justin Wingerter, The Denver Post, 10 Mar. 2025

Co-written by Gaines and Qasim Basir, The Dutchman stars André Holland as Clay, a successful Black man grappling with his wife Kaya’s (Zazie Beetz) infidelity, as well as his own self-perception versus how the world sees him because of the color of his skin. —Glenn Garner, Deadline, 8 Mar. 2025

For Kendrick, love takes the form of grace and forgiveness despite lust and infidelity. 45. —Stephen Kearse, Vulture, 4 Feb. 2025

The race got brutal as Election Day approached, with reports of marital infidelity and the emergence of a tape featuring Trump talking about grabbing women’s genitals. —Dan Alexander, Forbes, 1 Feb. 2025

Word History

Etymology

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

Rhymes for infidelity

• fidelity

Kids Definition

infidelity

noun

in·​fi·​del·​i·​ty ˌin-fə-ˈdel-ət-ē 

-(ˌ)fī-

plural infidelities

1

: lack of faith in a religion

2

: unfaithfulness especially to one's husband or wife