Polyandry

Polyandry (Greek: poly—many, andras—man) is a form of polygamy whereby a woman takes two or more husbands at the same time. In zoology, polyandry is a mating system involving a female and two or more males. Most broadly, polyandry refers to sexual relations with multiple males, within or without marriage. Polyandry is contrasted with polygyny, involving one male and two or more females. Polyandry is also distinct from group marriage, involving plural participants of each sex.

Polyandry is prohibited by Judaism, Islam, and the vast majority of Hindu and Christian denominations; neither is it legally recognized in most countries, including those that permit polygyny. Even in cultures where it has been known, it is and has been extremely rare, and then only in particular and limited circumstances. In those cultures, the husbands were almost always from the same family. For example, the form of polyandry in which a woman is married to two or more brothers is known as fraternal polyandry, and it is believed by many anthropologists to be the most frequently encountered form.

Read more about Polyandry:  Polyandry and Various Societies, Polyandry in Zoology