Polygamy
Polygyny
noun, の adjective
One husband, many wives. Sounds a bit sketchy. This is polygamy.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well. Just note that the 一 gets changed to いっ and the 夫 gets changed to ぷ from ふう for some reason. You can imagine that this is because when you are the type that has many wives, you're probably the type who makes them clean up your poo for you as well.
日本もかつては一夫多妻がみとめられていました。
Japan used to approve of polygamy too.
「一夫多妻せいとか、ありえないよな」とビエトが非難するように言うと、「その非難、自分に向けた方がいいんじゃねぇか?」とコウイチが笑って言い返した。
"I can't believe polygamy exists," Viet said accusingly. "You can turn that finger around,” Koichi retorted with a smile.
全ての男性が一夫多妻制を支持する訳じゃない。
It’s not like all men support polygamy.