I saw this thread reappear, and noted this never got answered as succinctly as it should be:
It's about being "Scripturally-correct," since that is a good goal, especially when folks don't understand.
Here are the words to understand:
Polyandry - ONE woman, MULTIPLE Husbands. (Biblically, that's called "adultery".)
Polygyny - ONE man, multiple wives. Which is Scripturally correct, and examples abound.
Polygamy - ANY or all of the above. And therein lies the rub.
While most folks (especially LDS, FLDS) would use the term polygamy, and ONLY mean the one (correct) variation - the word includes that other option that is forbidden in Scripture.
So, I personally prefer the term "polygyny"; that way, not only is there no confusion, but if someone asks, the explanation includes the Truth from Scripture in the process.
PS> As for the kinda revolting nuvo-PC term "polyamory" - it means "love is love," yuk. Not just all of the above, but no commitment required, no relation to the Bible whatsoever, and the participants need not even have the genitalia YHVH gave them...