A person who performs an exorcism. In Roman Catholicism, a priest who has been trained and authorized to perform a special rite for this purpose, made famous by the movie of the same name.
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...