abbreviation for Operating Thetan: 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?-n), 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 0?-n or "theta to the nth degree," meaning unlimited or vast. —ESTO - Handling Personnel, Part I Approved Glossary