Polygamy

Polygamy, marriage to more than one spouse at a time. The most typical forms of polygamy have been polygyny, in which cowives share a husband, or polyandry, in which cohusbands share a wife. However, same-sex marriage may instigate new forms of polygamy. Similar but without the commitment of marriage is polyamory, having or desiring multiple intimate relationships at the same time with the full knowledge and consent of all parties involved.

The term polygamy is often used as a synonym for polygyny, which appears once to have been fairly common worldwide. Nowhere, however, have any of these been the exclusive form of marriage.