Recent news reports regarding various issues related to the practice of polygamy, especially focusing on groups in Southern Utah, Arizona and Texas, have used terms such as "fundamentalist Mormons," "Mormon sect" and "polygamous Mormons" to refer to those who practice polygamy.
There is no such thing as a "polygamous" Mormon. Mormon is a common name for a member of The Church of Jesus Christ of Latter-day Saints. The Church discontinued polygamy more than a century ago. No members of the Church today can enter into polygamy without being excommunicated. Polygamist groups in Utah, Arizona or Texas have nothing whatsoever to do with The Church of Jesus Christ of Latter-day Saints.
When referring to people or organizations that practice polygamy, terms such as those listed above are incorrect. The Associated Press Stylebook notes: "The term Mormon is not properly applied to the other ... churches that resulted from the split after [Joseph] Smith's death."
More information on polygamy in Church history
Other related corrections and clarifications:
Fundamentalist Mormons, The Toronto Star, 6 February 2002
30,000 Mormon Polygamists, USA Today, 12 February 2002
Mormon Tom Green, Court TV, 3 June 2002
Tom Green, Polygamist coverage, BBC, Australian newspapers, 5 September 2002