Adultery is generally defined as consensual sexual intercourse by a married person with someone other than their lawful spouse. As there is usually an implicit or explicit agreement between spouses to not have sex outside the marriage the common synonym for adultery is infidelity or unfaithfulness. By extension these concepts may apply for other sexual activities outside the marriage. The sexual partner of a person committing adultery is often referred to in legal documents (especially divorce proceedings) as a co-respondent, while the person whose spouse has been unfaithful is often labeled a cuckold; originally, the latter term was applied only to males, but in more recent times women have been characterized in this way too.
The marriage in which both spouses agree that it is acceptable to have sexual relationships with other people is termed open marriage and the resulting sexual relationships are not considered adultery, at least from a non-legal standpoint. The law in some areas may not recognize open-marriage agreements and thus such extramarital sex may be considered adultery regardless. Sometimes only one party in an open marriage will opt to have other sexual relationships, in which case the one who does not do so is referred to as a wittol: sometimes called a "contented cuckold".
Penalties for adultery
Historically adultery has been subject to severe sanctions including the death penalty and has been grounds for divorce under fault-based divorce laws. In some places the method for punishing adultery was traditionally stoning to death.
In many jurisdictions, adultery is still illegal. Enforcement of laws against adultery is often uneven. In the United States, while a number of states still retain adultery laws on the books, they are rarely enforced, if ever. In places where adultery laws are still commonly enforced, women are often punished more harshly than men, in some cases being considered guilty of adultery even when they did not consent to sex. In the original Napoleonic Code, a man could ask to be divorced from his wife if she committed adultery, but the adultery of the husband was not a sufficient motive unless he had kept his concubine in the family home.
In the U.S. Military, adultery is a chargeable offense.
- Definition of Adultery, usage and translations in many languages in Webster's Dictionary - the Rosetta Edition