Mormons use this term instead of polygamy. In 1843, this doctrine became part of LDS scripture until 1890 when “the Lord inspired Church President Wilford Woodruff to issue a statement that led to the end of the practice of plural marriage in the Church.” (lds.org) The LDS Church currently teaches that God’s standard is a marriage between one man and one woman. Many Mormons, however, believe there will be plural marriages in the celestial kingdom.
Dictionary of "Mormonese"
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