Feminist Mormon Housewives has hosted multiple discussions on FLDS and polygamy (I seem to recall even a meet up with women from the Yearning for Zion Ranch, but was unable to locate this post). "Fundamentalist" and similar terms don't seem to dominate there, though one guest-poster self-identified as a "fundamentalist Mormon" and clarified that in a follow-up, "I am a Mormon Fundamentalist. I ascribe to the early teachings of the Mormon faith."

BYU law professor Fred Gedicks, guest-posting at TimesAndSeasons, defines fundamentalist religion as one "guided by scriptural literalism and unchanging, uncompromising doctrines that reveal truth and reality, understood as ‘objective' in the Cartesian sense" and asks "Is the LDS church spiritual or fundamentalist? Does an answer depend on whether one focuses on culture, theology, membership, or leadership? Can a fundamentalist church, one that insists on unchanging and uncompromising truths, and scriptural literalism, retain mass appeal in contemporary U.S. society?"

Mormonism, it seems, has a fundamentalist strain, following the socio-religious definition used by Mauss and used by others. In spite of logical or theological objections, however, the dominant connotation of "fundamentalist" is likely to remain something like "polygamous break-off." Whether it's excessively literalist strains of interpretation in Gospel Doctrine class or polygamous families wearing older styles of homemade clothing coming into the Wal-Mart in S. Utah, I think I know it when I see it.