Term coined by parapsychologist Ian Stevenson to indicate an uninvited entity or communicator at a séance, usually un-known to medium or sitters.
Berger, Arthur S., and Joyce Berger. The Encyclopedia of Parapsychology and Psychical Research. New York: Paragon House, 1991.
Stevenson, Ian. "A Communicator Unknown to Medium and Sitter." Journal of the American Society for Psychical Re-search 64 (1970).