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
See all Synonyms & Antonyms 
Example Sentences
She was convinced that her husband was guilty of infidelity. He has admitted to a number of marital infidelities.
Recent Examples on the Web The series centers on Jim Brockmire (Hank Azaria), who is a famed major league baseball announcer but suffers an embarrassing on-air meltdown due to his wife’s serial infidelity. 
Toby Grey, BGR, 16 Sep. 2022 According to sources, Rose's infidelity was the leading reason for the split. Alexandra Schonfeld, Peoplemag, 7 Sep. 2022 For my old friends who worked with me in the days of paper and ink who remain internal combustion die-hards, understand that embracing this new form of supercar is not an act of infidelity. Mark Ewing, Forbes, 14 Aug. 2022 Since then, the family’s every move on social media has sparked fresh cycles of speculation and led to further allegations about Lopez, including claims of infidelity. Kat Tenbarge, NBC News, 22 July 2022 Days before True's birth, photos and videos surfaced of Thompson and another woman that prompted allegations of infidelity. Sophie Dodd, PEOPLE.com, 20 July 2022 Some research has found that a married man’s losing his job is more likely to lead to divorce than is infidelity on his part. Kevin D. Williamson, National Review, 13 May 2021 The affair begins in high comedy and ends in sadness after the two discover that infidelity is terrifically hard to schedule. New York Times, 23 Mar. 2021 She is divorced due to her ex-husband’s infidelity. Annie Lane, oregonlive, 10 Aug. 2022 See More
Toby Grey, BGR, 16 Sep. 2022 According to sources, Rose's infidelity was the leading reason for the split. Alexandra Schonfeld, Peoplemag, 7 Sep. 2022 For my old friends who worked with me in the days of paper and ink who remain internal combustion die-hards, understand that embracing this new form of supercar is not an act of infidelity. Mark Ewing, Forbes, 14 Aug. 2022 Since then, the family’s every move on social media has sparked fresh cycles of speculation and led to further allegations about Lopez, including claims of infidelity. Kat Tenbarge, NBC News, 22 July 2022 Days before True's birth, photos and videos surfaced of Thompson and another woman that prompted allegations of infidelity. Sophie Dodd, PEOPLE.com, 20 July 2022 Some research has found that a married man’s losing his job is more likely to lead to divorce than is infidelity on his part. Kevin D. Williamson, National Review, 13 May 2021 The affair begins in high comedy and ends in sadness after the two discover that infidelity is terrifically hard to schedule. New York Times, 23 Mar. 2021 She is divorced due to her ex-husband’s infidelity. Annie Lane, oregonlive, 10 Aug. 2022 See More 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
infidelity
noun
1
as in adultery
lack of faithfulness especially to one's husband or wife infidelity can lead to divorce Synonyms & Similar Words
Relevance
- adultery
- betrayal
- faithlessness
- unfaithfulness
- disloyalty
- perfidy
- treachery
- inconstancy
- perfidiousness
- falseness
- deception
- duplicity
- deceit
- lying
- falsity
- treason
- double cross
- double-dealing
- sellout
Antonyms & Near Antonyms
- fidelity
- loyalty
- faith
- faithfulness
- devotion
- allegiance
- constancy
- fealty
- reliability
- steadfastness
- devotedness
- honesty
- trustworthiness
- dependability
- staunchness
2
as in betrayal
the act or fact of violating the trust or confidence of another the one thing that the political boss will not forgive is infidelity Synonyms & Similar Words
- betrayal
- treachery
- treason
- unfaithfulness
- faithlessness
- deception
- disloyalty
- perfidy
- backstabbing
- deceit
- abandonment
- falseness
- lying
- double cross
- falsity
- desertion
- two-timing
- sellout
- business
- duplicity
- fraud
- trickery
- guile
- informing
- two-facedness
- double-dealing
- snitching
- talebearing
Antonyms & Near Antonyms
- fidelity
- loyalty
- faithfulness
- devotion
- allegiance
- steadfastness
- fealty
- reliability
- trustworthiness
- dependability
- defense
- staunchness
- protection
- shield
- safeguard
3
as in cheating
a sexual encounter or relationship between a married person and someone other than their spouse had known about his wife's infidelities for years Synonyms & Similar Words
- adultery
- cheating
- misconduct
- unfaithfulness
- treachery
- promiscuity
- affair
- two-timing
- faithlessness
- disloyalty
- romance
- perfidy
- affaire
- infatuation
- inconstancy
- love
- intrigue
- perfidiousness
- flirtation
- falseness
- criminal conversation
- amour
- entanglement
- free love
- love affair
- fling
- attachment
- liaison
- passion
Antonyms & Near Antonyms
- fidelity
- faithfulness
- loyalty
- devotion
- allegiance
- dedication
- constancy
- steadfastness
- fealty
- devotedness