[from early IBM 'Simultaneous Peripheral Operation Off-Line', but this acronym is widely thought to have been contrived for effect]

vt. To send files to some device or program (a 'spooler') that queues them up and does something useful with them later. The spooler usually understood 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).

See also demon.