Paranormal Definitions: Incubus by Jennifer Scelsi

A lewd male demon who pursues women for sex. In Hebrew mythology, the incubus and his female counter part the Succubus, visit women and men in their sleep, lie and press heavily upon them, and seduce them. They can be conjured by witches, sorcerers and shamans. During the witch hysteria in Europe, incubus were believed to be instruments of the devil, tormenting people for the sole purpose of degrading their souls and perverting them to more vices. Incubus attacks are reported in modern possession cases.

Incubus is from the Latin word incubare, which means to lie upon. Victims usually feel a heavy weighty on top of them like  paralyzes them. Sometimes there is a sense of choking or suffocation. The Greeks referred  to the phenomenon as ephialtes, or the pouncer. Another Greek term is pnigalion, or suffocation. Pliny called it suppression or nocturnal illusions.