THX

1. A system of standards developed and founded by George Lucas in 1983 to help ensure the highest quality of sound in home theater systems and now computer games. Officially, THX is not short for anything. The official THX site can be found at http://www.thx.com.
2. Shorthand for thanks, THX is commonly used in chat rooms and text based communications. TNX is also sometimes used for saying thanks. Below is an example of how this could be used in chat.

User1: That's pretty funny.
User2: Heh yeah, AFK.
User1: Ok.
User2: Ok I'm back.
User1: WB
User2: Thx

Also see: 10x, Chat definitions, Game definitions, Sound definitions