Source : Free On-Line Dictionary of Computing

time slice
     
         (Or "time quantum", "quantum") The period
        of time for which a process is allowed to run uninterrupted in
        a {pre-emptive multitasking} {operating system}.
     
        The {scheduler} is run once every time slice to choose the
        next process to run.  If the time slice is too short then the
        scheduler will consume too much processing time but if it is
        too long then processes may not be able to respond to external
        events quickly enough.
     
        (1998-11-06)