Final answer:
The anthropological term for multiple men and women being married is polygamy, which includes polygyny and polyandry, with the former being more prevalent.
Step-by-step explanation:
In anthropology, the term used to describe the practice where multiple men and women get married is polygamy. This term encompasses both polygyny, where a man is married to multiple women, and polyandry, where a woman is married to multiple men; however, polygyny is more common globally. Polygamy is a socially sanctioned union that often signifies status and may arise due to various factors, including population growth, religious ideologies, social stressors, and economic strategies related to the labor contributions of children in agricultural societies.