Source : WordNet®

black magic
     n : the belief in magical spells that harness occult forces or
         evil spirits to produce unnatural effects in the world
         [syn: {sorcery}, {black art}, {necromancy}]

Source : Free On-Line Dictionary of Computing

black magic
     
         (Or "{FM}") A technique that works, though nobody
        really understands why.  More obscure than {voodoo
        programming}, which may be done by {cookbook}.
     
        Compare {black art}, {deep magic}, and {magic number}.
     
        (2001-04-30)