Source : Webster's Revised Unabridged Dictionary (1913)

Necromancy \Nec"ro*man`cy\, n. [OE. nigromaunce, nigromancie,
   OF. nigromance, F. n['e]cromance, n['e]cromancie, from L.
   necromantia, Gr. ?; ? a dead body (akin to L. necare to kill,
   Skr. na(?) to perish, vanish) + ? divination, fr. ? diviner,
   seer, akin to E. mania. See {Mania}, and cf. {Internecine},
   {Noxious}. The old spelling is due to confusion with L. niger
   black. Hence the name black art.]
   The art of revealing future events by means of a pretended
   communication with the dead; the black art; hence, magic in
   general; conjuration; enchantment. See {Black art}.

         This palace standeth in the air, By necromancy
         plac[`e]d there.                         --Drayton.

Source : WordNet®

necromancy
     n 1: the belief in magical spells that harness occult forces or
          evil spirits to produce unnatural effects in the world
          [syn: {sorcery}, {black magic}, {black art}]
     2: conjuring up the dead, especially for prophesying