Former Mormon. Person who at one time in there life been a member of the Church of Jesus Christ of Latter Day Saints.
"Why do you know every Disney Movie?"
"Because I'm a formon."
A former mormon (i.e. member of the so-called Church of Jesus Christ of Latter-Day Saints). Someone who wised up and realized just how utterly loony Mormonism is.
Often brought on by actually reading the Book of Mormon or studying the life of Joseph Smith.
See also jack mormon, exmormon, morg.
Some prominent formons include Warren Zevon, Eliza Dushku, the singer Jewel, Paul D. Boyer, William Shunn, etc.