A multi-user operating system based on the earlier (1960's) operating system Multics ("MULTiplexed Information and Computing Service"). BellLabs felt Multics was getting bloated, so they wrote their own system called Unix, which was "Multics without the balls" or "only one of whatever Multics was supposed to be a lot of".
See also:
http://www.webopaedia.com/TERM/U/UNIX.html
The UNIX Time-Sharing System
UNIX History (serious)
UNIX History (humourous)
JargonFile:UNIX
JargonFile:Multics
WikiPedia:UNIX
WikiPedia:Multics95 pages link to Unix:
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