Polygyny

Polygyny
       ("poly-") many
       ("-gyny") women.

Polygyny refers to a man marrying more than one wife.

The easy way to quickly recall the correct spelling and pronunciation of this term, polygyny, is by realizing that the "gyn" (of "-gyny") comes from the same root-word as found in the name of medical fields which specifically specialize in women's health, "GYNocology" and "ob/GYN" (obstetrics/GYNocology).

When most people use the more neutral term, "polygamy", they are usually only meaning this term here, i.e., polygyny.