SUCCUBUS, SUCCUBA
European Folklore
A type of Fiend
This is the medieval European female fiend of the night. The name is from the Latin Sub, under, and cubare, to lie down. Just like the INCUBUS that mounts a sleeping woman for the purpose of sexual relations, this is the female form that copulates with man in his sleep. It may take on any shape, male or female, but it usually appears in the semblance of he wife or lover, or it may be entirely invisible. During witch-hunts of the sixteenth and seventeenth centuries, women were often accused of being the SUCCUBUS of the DEVIL, with little chance of refuting such a charge.
Source: Spirits, Fairies, Leprechauns, and Goblins Encyclopedia