What does O.K. stand for?

Despite many alternative claims, the first appearance in print links the term O.K. to a political organization that supported the reelection of President Martin Van Buren.

The New York New Era of March 23, 1840, carried an article on the Democratic O.K. Club.

The initials stood for Old Kinderhook, a Van Buren epithet derived from his birthplace, Kinderhook, in southeastern New York State.

During the election campaign, the letters O.K. became a favorite, if mysterious, rallying cry.