Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online.The term polygamy (a Greek word meaning "the practice of multiple marriage") is used in related ways in social anthropology, sociobiology, sociology, as well as in popular speech. Polygamy can be defined as any "form of marriage in which a person has more than one spouse." In social anthropology, polygamy is the practice of marriage to more than one spouse simultaneously. Historically, polygamy has been practiced as polygyny (one man having more than one wife), or as polyandry (one woman having more than one husband), or, less commonly as group marriage (husbands having many wives and those wives having many husbands). In contrast, monogamy is the practice of each person having only one spouse. Like monogamy, the term is often used in a de facto sense, applying regardless of whether the relationships are recognized by the state (see marriage for a discussion on the extent to which states can and do recognize potentially and actually polygamous forms as valid). In sociobiology, polygamy is used in a broad sense to mean any form of multiple mating.