From the latin concubere, meaning "to lie beside", a concubus is a demonic entity or spirit who typically engages in sexual acts with humans during the night. Unlike its solely male counterpart, the incubus (from the latin incubere meaning "to lie upon") or its solely female counterpart, the succubus (from the latin succubere meaning "to lie beneath"), the concubus is a creature that in mythology and folklore changes its sexual organs in order to sleep with anyone it comes across, feeding on its victim's sexual and spiritual energy.