SPOOL really means

[utzoo!decvax!duke!mcnc!ncsu!fostel]

    If my memory serves me, the term "SPOOL" is originally derived from
    the phrase "similtaneous peripheral operation on line".  I find it
    hard to believe that the acronym was not constructed to match the
    more common meaning as in  a spool of tape. (Many moons ago, the more
    familiar "reel" of tape was not universal.)
    ----GaryFostel----