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

Naturally, such a law could’ve put an end to Gittes’ line of detective work; investigating and photographing infidelities is his bread-and-butter. —J. Kim Murphy, Variety, 22 June 2024

The strongly Republican 3rd District next door features an open-seat race following the retirement of Republican Rep. Jeff Duncan, who also faced accusations of marital infidelity. —Geoffrey Skelley, ABC News, 9 June 2024

Later, her own political aspirations often collided, at times extremely uncomfortably, with her husband’s infidelity and his postpresidential work. —Reid J. Epstein, New York Times, 17 May 2024

However, the ultimate test of their relationship came in 2015 when Josh was involved in a data breach linked to the infidelity website Ashley Madison. —Emily Weaver, Peoplemag, 13 May 2024

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

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