Source : Free On-Line Dictionary of Computing

supervisor mode
     
        (Or "{supervisor state}") An execution mode on some processors
        which enables execution of all instructions, including
        {privileged instruction}s.  It may also give access to
        different a {address space}, to {memory management} hardware
        and to other peripherals.  This is the mode in which the
        {operating system} usually runs.
     
        Opposite: {user mode}.
     
        (1995-02-15)