mux

1) In communication transmission systems, mux (pronounce muks, sometimes spelled "MUX") is an abbreviation for multiplexing, a device that sends multiple signals on a carrier channel at the same time in the form of a single, complex signal to another device that recovers the separate signals at the receiving end. The receiver is sometimes called a demux (or "DEMUX").

2) On the Internet, a MUX is a multi-user text game played over the Internet, using the TinyMUX server. This kind of game started with the MUD (multi-user dungeon) movement.