Poltergeists are a form of ghost. Usually these spirits are linked strongly to and reside exclusively in one area, usually a home. These spirits have existed in their immaterial form for quite some time. Because they usually reside exclusively in one area, they usually do not learn much magic (unless the place they reside in has the books and required materials, i.e. a wizard's home). Instead, they have spent their time mastering manipulating their physical environment only. Poltergeists are visible but transparent. But, if they wish to they may go completely invisible and inaudible at will. Therefore, without outside magical aid, individuals attacking a poltergeist should receive a -10 modifier to their strikerolls. Poltergeists generally will only attack if an individual's presence becomes annoying to the ghost. This also depends on the demeanor of the poltergeist.
As with all other ghosts, strictly material objects do no damage to poltergeists. Magical weaponry will do normal damage to them. Spells will do their normal amounts of damage if the force causing the damage is magical (i.e. a rock telekinetically thrown at an poltergeist will do no damage.) All ghosts can function well at anytime of day in any climate.
Reality
(1840-1850) German
polter = to make noise, to rattle
geist = ghost
Poltergeists are ghosts that make strange noises in the home. (i.e. wind blowing, chains rattling, moaning..etc.)