noun.
The state or practice of having several wives at the same time; plurality of wives; marriage to several wives - H. Spencer
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
noun.
having more than one wife at a time
Word Usage
"That latter is exceedingly rare, which is why the researchers use the term polygyny and not the often misused polygamy, which refers to multiple partners for both sexes."