polygynist
/ˌpɒlɪˈɡaɪnɪst/Definitions
1. noun
A person who practices or advocates polygyny, the practice of having more than one wife at a time.
“The polygynist community in the Middle East has been a subject of interest among anthropologists.”
2. noun
A person who believes in or advocates polygyny.
“The polygynist movement has been gaining momentum in some African countries.”