The word Mormon has multiple meanings. First, it is a nickname for the members of The Church of Jesus Christ of Latter-day Saints. This nickanme comes from the fact that Mormons believe that the Book of Mormon is a volume of scripture in addition to the Bible. It was translated by the Prophet Joseph Smith by the power of God. From this comes Mormon, Mormon Church, and Mormonism, all refering to the membership and beliefs of The Church of Jesus Christ of Latter-day Saints.
The Book of Mormon, in turn, gets its name from a prophet/historian named Mormon . Mormon lived on the American continent sometime in the late fourth century A.D. (ca. A.D. 311-385). During his life he kept the records of his people, called the Nephites, and eventually creating an abridement of their history which is the record now called theBook of Mormon . In addition to being a prophet and historian, he was also a great military leader for his people, but because of their wickedness and rebellions, they were destroyed in a major war sometime around A.D. 385. Mormon’s son, Moroni, who escaped the general slaughter of his people, completed the record after his father’s death and buried the record, which was engraved on Golden plates, in a hill in what is now upper state New York. Hundreds of years later,Moroni returned as an angel of God and appeared to Joseph Smith to show him where the records were buried.
In addition to these, the word Mormon appears in other places within the text of the Book of Mormon. Two books within the Book of Mormon, have it as part of their title. “The Words of Mormon,” and the “Book of Mormon,” were written primarily by the prophet Mormon and deal with Mormon’s own time period and teachings. Finally, in another section within the Book of Mormon, called the Book of Mosiah, Mormon refers to an oasis where a prophet named Alma baptized followers of Jesus Christ on the American continent.
When asked once what the word “Mormon” meant, Joseph Smith speculated that it could be tranlated as “More Good” (see Teachings of the Prophet Joseph Smith, pp 299-300).