Extramarital sex is any act of copulation outside of marriage. Accordingly, these constitute sexual acts between two persons who are not married with each other. The term may also apply to a single person having sex with a married person.
Where extramarital sexual relations do not breach a sexual norm, it may be referred to as consensual non-monogamy (see also polyamory). Where extramarital sexual relations do breach a sexual norm, it may be referred to as adultery or non-monogamy (sexual acts between a married person and a person other than the legal spouse), fornication (sexual acts between unmarried people), bigamy, philandery, or infidelity. These varying terms imply both immoral or religious consequences, charged whether via civil law or religious law.