1. The spirit who acts as a kind of manager through which other spirits communicate to the medium during a séance.
2. In science (and in the scientific investigation of the paranormal—parapsychology), experimental proceedures instituted to prevent extraneous factors from influencing the results of an experiment.
Readers, please enjoy this guest blog post by Sandra Kynes, author of several books, including The Herb Gardener's Essential Guide, Plant Magic, and the new Witches' Encyclopedia of Magical Plants, among many others.
Although a few old books...