[from early IBM ‘Simultaneous Peripheral Operation On-Line’, but is widely thought to be a backronym] To send files to some device or program (a spooler) that queues them up and does something useful with them later. Without qualification, the spooler is the print spooler controlling output of jobs to a printer; but the term has been used in connection with other peripherals (especially plotters and graphics devices) and occasionally even for input devices. See also demon.