necromancy

Circa 1300, entering Middle English as nigromancye, from Old French nigromancie, from Medieval Latin nigromantia, from Latin necromantia, from Ancient Greek nekromanteía, a compound of nekrós ("dead") and manteía ("divination").

The Medieval Latin spelling swapped in niger, meaning "black," under the influence of the idea of the "black art," which is why English long spelled it nigromancy. The modern necromancy spelling, closer to the original Greek, was adopted in the mid-1500s.

By surface analysis it breaks down as necro- + -mancy, the same -mancy ending found in words for other forms of divination.