It stands for Time Honored eXcellence.
Despite the common believe of THX1138 and good ol GL, This is a sound format origionally developed by Steven Speilburg.
You see, way back in the day Steven Speilburg and George Lucas used to kick it. They met in college and were roomates.
This is how it went down.
Gl and SS used to hang out. They met in college and were pot smoking buddys. They would talk till the late hours of the night, spinning tales of fantasy and adventure.
They were the best of friends. That is, untill Rebecca came into the story. Rebecca Chu, Chu being the family name of asian decent. She started dating George Lucas and eventually starting demanding all of his time. Steven speilberg felt like a third wheel and evenrually stopped hanging out with them. It was then that Steven Speilberg decided he wanted to throw his hand into high end audio. He started out by building an amplifier that was of tru high end calibur. He decided to call this THX Time Honored Xcellence, which he decided would be the motto of his High end audio company.
Well, one day Steven went to a kegger and brought along his amplifier to show off to some of his buddys. Low and behold, there was Rebecca Chu. She was there partying and ol george lucas was nowhere to be found, turns out he was real sick.
Steven and Rebecca started talking a little bit, and before you know it, they were making out on the couch.
One of George Lucas's buddys was there and called up george and told him the low down. Well, george was furious! he got his sick ass outta bed and went to the party in time to see Steven Speilberg and Rebecca Chu making out on the couch! He wwas so pissed off he diddnt know what to do. He started yelling and everything blew up. A big shouting match occurred, he called Rebecca a hairy gorilla, and stormed away, but on the way he paused when he saw the THX amplifier that steven speilberg made. Figuring he would get his revenge, he swiped the THX amp, and left town.
Poor george never got over that. So when he had a chance to get a movie made, he knew that Steven who also decided to take a career in the movie industry would surly hear of the movie and temember him. He called the movie THX1138. 1138 being the time they would get high between college classes.
George further decided to insult Rebecca Chu by naming the Wookie in starwars Chu-bacca, after Rebecca Chu.
If you watch thier movies they are always mad-dogging eachother. Rebecca Chu has since then become a man with the magic of sex change procedures, and has disappeared since.
Anyways, George ended up claiming the whole THX thing, which will always be associated with George Lucas. A way of showing Steven Speilberg that George doesent take crap.
Anyways, that is what really happened.