What does adultery mean?
Adultery is voluntary sexual intercourse between a married person and someone other than their spouse. It is one of the oldest concepts in moral and legal thought, condemned in the Ten Commandments and regulated or punished by societies across history. In modern usage the word carries a formal, often legal or literary tone — appearing in divorce proceedings ('grounds of adultery'), religious teaching, and fiction — while everyday conversation tends to favor 'cheating,' 'infidelity,' or 'having an affair.' The word implies a breach of marital fidelity rather than mere premarital sex, which is called fornication. Adultery has been grounds for divorce in many legal systems, and in some countries it remained a criminal offense well into the twenty-first century. Related forms include 'adulterer' and 'adulteress' for the individuals involved and the adjective 'adulterous.'
nounVoluntary sexual intercourse between a married person and someone who is not their spouse.
- Voluntary sexual intercourse between a married person and a person who is not their spouse.
"The novel's plot hinges on an act of adultery that shatters two families."
"Under the old law, a husband could divorce his wife on the grounds of adultery alone."
"The scandal broke when photographs revealed the senator's adultery."
Rarely used in the plural; the word is almost always treated as an uncountable mass noun referring to the act or offense generally.
"The chronicle catalogued the king's adulteries over three decades."
In much of the world, adultery was literally a crime until surprisingly recently — South Korea only decriminalized it in 2015.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of adultery
Adultery comes from the Old French 'avouterie'/'adultère', from Latin 'adulterium', meaning unchastity or extramarital sex, itself probably derived from 'adulter', an adulterer. The Latin root may connect to 'alter', meaning 'other', suggesting the idea of giving oneself to another. English adopted the word in the late medieval period via French and Latin. The same root gives us 'adulterate', originally meaning to corrupt or defile, which came to describe making goods impure — a semantic shift from moral contamination to physical contamination.
Related word forms
How adultery is actually used
Adultery is a formal, somewhat legal or moral register word; in everyday speech people more often say 'cheating' or 'having an affair.' It carries strong moral and religious connotations, being condemned in most major religions (notably in the Ten Commandments). In some jurisdictions it remains a criminal offense or a ground for divorce; elsewhere it is purely a private matter. The gendered nouns 'adulterer' (typically for a man) and 'adulteress' (for a woman) are now dated and less commonly used.
Easily confused with adultery
To adulterate means to make something impure or poorer in quality by adding another substance, whereas adultery refers to sexual infidelity by a married person — both share the same Latin root but have entirely different meanings.