an abbreviation for Operating Thetan: a state of beingness. It is a being "at cause over matter, energy, space, time, form and life." Operating comes from "able to operate without dependency on things," and Thetan is the Greek letter theta (0), which the Greeks used to represent thought or perhaps spirit, to which an n is added to make a noun in the modern style used to create words in engineering. It is also 0n or "theta to the nth degree," meaning unlimited or vast. A thetan beyond the state of Clear advances through pre-OT levels (such as OT III) to the full state of Operating Thetan. —ESTO - Estos Instant Hat, Part II Approved Glossary