polygamy

The practice of having more than one spouse at the same time. It is found among many peoples. Normally it has been confined to the wealthy and to chiefs and nobles who can support several women and their offspring, as among ancient Egyptians, Teutons, Irish, and Slavs. Islam limits the number of legal wives a man may have to four. Certain Christian sects - for example, the Anabaptists of Münster, Germany, and the Mormons - have practised polygamy because it was the norm in the Old Testament.

When the norm is for one husband and several wives, it is called polygyny; for one wife and several husbands, polyandry. The most common expectation (although not necessarily the reality) was for polygyny. Polyandry was a very rare form of marriage, expected only where maintaining spare property or family heritage was important to the survival of the culture.