Adultery

noun

1. Sexual intercourse by a married person with someone other than their spouse.

   "She engaged in adultery because her spouse has a low libido, while hers is very high."

2. Lewdness or unchastity of thought as well as act, as forbidden by the seventh commandment.
3. Faithlessness in religion.
4. The fine and penalty formerly imposed for the offence of adultery.
5. The intrusion of a person into a bishopric during the life of the bishop.