There seems to be a range of adjectives to describe such people, and the noun for such an action is infidelity, but I couldn't find a noun that can be commonly used to describe the unfaithful person.

he/she has been cheating on his/her spouse/partner, he/she is a __________

(This train of thought was prompted by somebody's garbled answer here that was giving an example involving infidelity.)

Please note: 'adulterer/ adulteress' is an obvious option, but its legal definition presupposes marriage, at least here in India, so I should like to find some other word to fit this question.

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    – tchrist
    Jun 24, 2017 at 21:12

5 Answers 5


To my mind the most descriptive idiom is two-timer, the noun form of two-time

- to be unfaithful to (a lover or spouse)
- to double-cross.

  • But this does not cover the general case when the unfaithful cad may have a whole string of partners and be an n-timer.
    – KalleMP
    Jun 21, 2017 at 21:23
  • 1
    @KalleMP he's a two-timer for every single pair
    – Mitch
    Jun 24, 2017 at 21:22

Philanderer/ noun form to describe one who philanders

Philander [fi-lan-der] verb (used without object)

  1. (of a man) to make love with a woman one cannot or will not marry; carry on flirtations.


Debauchee [deb-aw-chee, -shee]/ noun

  1. a person addicted to excessive indulgence in sensual pleasures; one given to debauchery.


Reprobate [rep-ruh-beyt]/ noun

  1. a depraved, unprincipled, or wicked person:

Some of these terms seem to be more gender specific, but I believe that the intended application would be understood regardless of gender. Though it is anachronistic, the essence of the description could be applied to any person acting as such.

  • Excellent answer! Now I remembered 'philanderer' -- thanks a lot, I updates! Jun 21, 2017 at 18:59

He has been cheating on his wife, he is a cad.

  • 'cad' is not a noun
    – Mitch
    Jun 21, 2017 at 15:47
  • 3
    @mitch, Yes it is.
    – Ben
    Jun 21, 2017 at 15:58
  • 2
    He may be a cad, but not all cads are cheaters. He is equally a jerk, an asshole, a sleaze, scum, a heel, etc Jun 21, 2017 at 16:02
  • 1
    @EnglishStudent That depends on if you think cheating automatically makes you a cad, I guess. It's a subjective thing. Jun 21, 2017 at 16:11
  • 1
    @Mitch cad doesn't mean unfaithful. And labels like cad don't encapsulate an entire person. A person can be faithful and be a cad, or have been unfaithful but otherwise be kind, generous, and trustworthy. Jun 21, 2017 at 16:19

Depending on the context, you might consider rat.

Oxford dictionary online:


  1. informal A despicable person, especially a man who has been deceitful or disloyal.

‘her rat of a husband cheated on her’

  • Thank you. I think 'rat' is applied to the person as meaning despicable because they cheated? Jun 21, 2017 at 20:21

New Oxford American Dictionary

Fornicator (noun): (of two people not married to each other) have sexual intercourse.

  • 4
    "Fornicator" doesn't imply any sort of unfaithfulness, though.
    – user89175
    Jun 21, 2017 at 20:08

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