Okay you want to get hung up on a definition to somehow justify talking to the dead.
Webster:
necromancy: conjuration of the spirits of the dead for purposes of magically revealing the future or influencing the course of events.
Encarta:
necromancy: 1. prediction using spirits: the practice of attempting to communicate with the spirits of the dead in order to predict or influence the future.
“INFLUENCING THE COURSE OF EVENTS.” What do you think you are trying to do with a prayer? You are asking for something from the dead (intercession/mediation), and trying to influence the course of events.
Just as Campion said, you fail to accept the fact that these faithful "dead" are actually alive in Christ.
When we pray to God for something, are we "trying to influence the course of events"? In a sense, we are doing that with certain prayers. None of these saints have any power of their own other than their prayer. God does the heavy lifting.
Okay. Was Jesus practicing necromancy at the Transfiguration?