多配偶制 = polygamy
poly（多）+gamos（婚姻），一般指一夫多妻制。
例句
The Mormons, organizing themselves in response to a religious vision, practiced polygamy in all their settlements.
生活例句
- traditions of polygamy
- has led to the perception of polygamy
- but anthropologists call it effective polygamy.
- Polygamy is widely practiced in Kenya.
- a lot of modern societies still engage in some forms of polygamy.