Short answer: Unix stands for UNiplexed Information and Computing System. (It was originally spelled "Unics.")

Long answer: Coined in 1969 to describe a specific computer operating system, the term "Unix" now covers a whole host of variations, including Linux, FreeBSD, and Solaris. The name was intended as a pun on an earlier system called "Multics" (Multiplexed Information and Computing Service).

That sidesplitting pun is the key to understanding the acronym, since the word "uniplexed" doesn't seem to mean anything in particular. ("Multiplexed" refers to a communications system able to carry many messages simultaneously.)

Here's how we found all this out:

Since we were looking for a specific term, a dictionary seemed like a good place to go. By entering the terms "computer" (we knew that "Unix" related to computers) and "dictionary" into the Yahoo! search box, we landed at the Computers and Internet > Dictionariescategory.

There, we clicked off to both the PC Webopaedia and the Free On-Line Dictionary of Computing, where we began to get a sense of the meaning and history of Unix.

At the Webopaedia, we spotted a promising crosslink to the Unix FAQ, where we got confirmation of the punning aspect of the term.