Polygyny

(n.) The state or practice of having several wives at the same time; marriage to several wives.

Thesaurus Entries

beena marriage, common-law marriage, companionate marriage, concubinage, deuterogamy, left-handed marriage, levirate, leviration, love match, marriage of convenience, monandry, monogamy, monogyny, morganatic marriage, picture marriage, polyandry, polygamy, polygyny, trial marriage, trigamy