(being written concurrently with an essay about Andrew Jackson, a winning combination)
Besides the more general application which Webster 1913 gives, the term Antimason also refers to a member of the political party of Antimasons, best known for fielding William Wirt as a candidate for president. Wirt's run for the executive office was triggered by the fact that the two major candidates, Andrew Jackson and Henry Clay were both Freemasons.
The party's strength lay in New England and the Middle Atlantic, where a number of traumatic events occured as a result of various Masons revealing the secrets of the organization. Those who disclosed the secrets were often killed or imprisoned. The morality of Mason meetings was questioned, where they were suspected of drinking, gambling, and carousing. Freemasonry also had religious overtones, what with all the temples and such. Neither Catholics nor Protestants supported the sectarian tendencies of the society.
In the 1832 election, Wirt made history as the first significant third-party candidate, receiving seven of two hundred eighty-six electoral votes, and 33,108 popular votes (out of about 1,210,000 cast). The Anti-Mason movement soon faded, despite the fact that innumerable presidents after Jackson were members of the fraternal order. Wirt's showing would be the last such success.
Update: As of yesterday, the Freemasons are our accepted rulers, and this writeup is no longer a correct representation of history. My apologies to our lords and masters. Ukna barak whwea gaor rsaa...