Source : Webster's Revised Unabridged Dictionary (1913)

Spooler \Spool"er\, n.
   One who, or that which, spools.

Source : Free On-Line Dictionary of Computing

spooler
     
         Software or hardware to which data is
        {spool}ed and which processes that data (e.g. prints it) in the
        {background}.
     
        (1995-03-25)