A state purportedly produced by Dianetic processing, described as being free of one's reactive mind. According to Hubbard's book Dianetics, a clear has perfect memory and improved eyesight, and no longer suffers from psychosomatic illnesses.
This site discusses Dianetics, Scientology, and related topics, but is not affiliated with the Church of Scientology in any way. You can find their official site at www.scientology.org