When referring to Church members, the term “Latter-day Saints” is preferred, though “Mormons” is acceptable.
"Mormon” is correctly used in proper names such as the Book of Mormon, Mormon Tabernacle Choir or Mormon Trail, or when used as an adjective in such expressions as “Mormon pioneers.”
The term “Mormonism” is acceptable in describing the combination of doctrine, culture and lifestyle unique to The Church of Jesus Christ of Latter-day Saints.
When referring to people or organizations that practice polygamy, the terms “Mormons,” “Mormon fundamentalist,” “Mormon dissidents,” etc. 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.”