Definitions for "dybbuk"
the wandering soul of a dead person, or a demon, that enters the body of a living person and controls that body's behavior. It may be exorcised by religious rites.
A dispossessed spirit which seeks to possess a body. Originally these were believed to be a specific type of demon. Later they were said to be spirits of evildoers denied transmigration. Punished with wandering and beatings by attendant angels, they seek refuge in a living body. They may wish harm or revenge, or redemption from a pious rabbi so they might be forgiven and move on. In some cases the dybbuk is not evil, but simply a lost or misplaced soul, such as one who died unnaturally or who was not properly laid to rest. The common theme is a desire for the flesh to escape the torments of a nomadic spiritual existance. Depending on the dybbuk, one might be possessed for a long time and never know it.
A Jewish ghost that takes possession of people.