ghost

In superstitious belief, a ghost is the apparition of a dead person. The Merriam-Webster Online Dictionary defines ghost as " the soul of a dead person believed to be an inhabitant of the unseen world or to appear to the living in bodily likeness". MSN Encarta dictionary defines ghost as "the supposed spirit of somebody who has died, believed to appear as a shadowy form or to cause sounds, the movement of objects, or a frightening atmosphere in a place".

According to skeptics, "ghost sightings" are nothing but misidentification of known phenomena; for example, change in air pressure changes in a home causing the doors to slam, or lights from a passing car reflected through a window at night. These events are sometimes misidentified as ghosts. Pareidolia, an illusion or misperception whereby a distinct image is perceived in a collection of matter, is one of the causes which led people to believe they have seen ghosts.