(plural: incubi) a creature of male form who has sexual intercourse with its creator in dreams and fantasies. Etymology: Middle English, from Late Latin, from Latin incubare, "to lie on."
"The terms incubus and succubus have been applied indiscriminately by the Church Fathers to elementals. The incubus and succubus, however, are evil and unnatural creations, whereas elementals is a collective term for all the inhabitants of the four elemental essences. According to Paracelsus, the incubus and succubus (which are male and female respectively) are parasitical creatures subsisting upon the evil thoughts and emotions of the astral body. These terms are also applied to the superphysical organisms of sorcerers and black magicians. While these larvæ are in no sense imaginary beings, they are, nevertheless, the offspring of the imagination. By the ancient sages they were recognized as the invisible cause of vice because they hover in the ethers surrounding the morally weak and continually incite them to excesses of a degrading nature. For this reason they frequent the atmosphere of the dope den, the dive, and the brothel, where they attach themselves to those unfortunates who have given themselves up to iniquity. By permitting his senses to become deadened through indulgence in habit-forming drugs or alcoholic stimulants, the individual becomes temporarily en rapport with these denizens of the astral plane. The houris seen by the hasheesh or opium addict and the lurid monsters which torment the victim of delirium tremens are examples of submundane beings, visible only to those whose evil practices are the magnet for their attraction." - Secret Teachings of All Ages (1928) by Manly P. Hall