Ectoplasm

Full definition of ectoplasm

(countable and uncountable; plural ectoplasms)

(parapsychology) The visible substance believed to emanate from the body of a spiritualistic medium during communication with the dead.
(parapsychology) An immaterial or ethereal substance, especially the transparent corporeal presence of a spirit or ghost.
(cytology) The outer granule-free layer of cytoplasm.