So Clamp's X would have the same meaning too. Everyone would know the ever Famous 'X Files' with FBI agents Scully and Molder that try to explain the cases of the supernatural, the X in that would be a same meaning to that. Words that contain X such as X-ray, X-generation, X Day (an unknown day) are often used in everyday language, this X brings a sense of something unknown or not being able to be understood. 2) the 24th letter in the English Alphabet 3) The Roman Numeral for the number 10. One the title X makes perfect sense: Definitions of X 1) a symbol to often symbolize an unknown in mathematics. X is an excellect film if you understand it, nothing irritates me more than a bad movie critic, to be a good one you must understand what you are critiquing.