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

On a broader scale, the widespread prevalence of financial infidelity also reflects gaps in financial literacy and communication, underscoring the need for better education and resources to address these issues. —Barbara A. Perry, Newsweek, 28 Jan. 2025

That lack of communication can contribute to financial infidelity, when one or both partners lie about or hide financial information. —Lorie Konish, CNBC, 27 Jan. 2025

The play follows Moorish commanding warrior general Othello as he is manipulated by his ambitious lieutenant, Iago, into suspecting his wife, Desdemona, of infidelity. —Dave Quinn, People.com, 27 Jan. 2025

In one of the most heated moments of the hourslong hearing, Democratic Sen. Tim Kaine of Virginia questioned Hegseth about his history of infidelity in his three marriages. —Caitlin Yilek, CBS News, 24 Jan. 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

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