Thetan

From Non-Violent Uprising

A thetan is LRH-speak for a soul. Hubbard says that every person living on earth has (or is) a thetan that has lived through countless different reincarnations for the past trillion billion quadrillion years, and Lord knows we have no reason to doubt him. Thetans that aren't currently serving time as somebody you know are probably stupidly hanging around the human body in places you'd least expect them—under your kneecaps, in the small of your back, under David Miscavige's hairpiece—and are referred to as "body thetans". Much of the middle to upper OT levels deal with how to get the pesky things off yourself, because apparently they cary bad juju.

The term thetan does in fact come from the greek letter theta (θ). Although the details are not entirely clear to the editors of this wiki, it's known that some of Hubbard's lectures discuss "theta power" and that "thetan" is pronounced similarly (that is, it rhymes with "Satan").