Source : Free On-Line Dictionary of Computing

IRIX
     
         /ir'iks/ The main {operating system} used
        by {Silicon Graphics} {workstations} and {servers}.  IRIX is
        {multiprocessor} and {multi-threaded}.  It incorporates
        substantial functionality from {UNIX} {System V}, Release 4.1
        and 4.2.
     
        (1997-06-17)