[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.