necromancer n.

c. 1300, nygromauncy, nigromauncie, "sorcery, witchcraft, black magic," properly "divination by communication with the dead," from Old French nigromancie "magic, necromancy, witchcraft, sorcery," from Medieval Latin nigromantia (13c.), from Latin necromantia "divination from an exhumed corpse," from Greek nekromanteia, from nekros "dead body" (from PIE root *nek- (1) "death") + manteia "divination, oracle," from manteuesthai "to prophesy," from mantis "one who divines, a seer, prophet; one touched by divine madness," from mainesthai "be inspired," which is related to menos "passion, spirit" (see mania). The spelling was influenced in Medieval Latin by niger "black," on notion of "black arts;" the modern English spelling is a mid-16c. correction. Related: Necromantic.