(from German Polter, “noise” or “racket”; Geist, “spirit”), in occultism, a disembodied spirit or supernatural force credited with certain malicious or disturbing phenomena, such as inexplicable noises, sudden wild movements, or breakage of household items. Poltergeists are also blamed for violent actions—throwing stones or setting fire to clothing and furniture. Such events are said to be sporadic, unpredictable, and often repetitive.

According to popular belief, a poltergeist's activity appears to concentrate on a particular member of a family, often an adolescent, its object being harassment or, rarely, physical harm. When strangers are present, the unusual phenomena often cease. A large portion of those reported to be victimized suffer from hysteria. In many instances, the activities attributed to poltergeists have been explained as natural phenomena—e.g., the normal creaking of boards in an old house. See also kobold.