UNIX

UNIX: /yoo'niks/ n.  [In the authors' words, "A weak pun
   on Multics"] (also `Unix') An interactive time-sharing system
   invented in 1969 by Ken Thompson after Bell Labs left the Multics
   project, originally so he could play games on his scavenged PDP-7.
   Dennis Ritchie, the inventor of C, is considered a co-author of the
   system.  The turning point in UNIX's history came when it was
   reimplemented almost entirely in C during 1972--1974, making it the
   first source-portable OS.  UNIX subsequently underwent mutations
   and expansions at the hands of many different people, resulting in
   a uniquely flexible and developer-friendly environment.  By 1991,
   UNIX had become the most widely used multiuser general-purpose
   operating system in the world.  Many people consider this the most
   important victory yet of hackerdom over industry opposition (but
   see {UNIX weenie} and {UNIX conspiracy} for an opposing point
   of view).  See {Version 7}, {BSD}, {USG UNIX}.

   Some people are confused over whether this word is appropriately
   `UNIX' or `Unix'; both forms are common, and used interchangeably.
   Dennis Ritchie says that the `UNIX' spelling originally happened in
   CACM's 1973 paper because "we had a new typesetter and troff had
   just been invented and we were intoxicated by being able to produce
   small caps."  Later, dmr tried to get the spelling changed to
   `Unix' in a couple of Bell Labs papers, on the grounds that the
   word is not acronymic.  He failed, and eventually (his words)
   "wimped out" on the issue.  So both capitalizations are grounded
   in ancient usage.