Poltergeist

A Poltergeist is a chaotic spirit which is similar to a ghost. The main difference is that a poltergeist typically moves objects and people with physical force. It's name comes from the German poltern meaning "rumble", and geist, meaning ghost or spirit.

Poltergeists cause vandalism, malicious mischief and chiefly frustrate and aggravate living persons. They can unscrew chandeliers, write rude words on chalkboards, throw water balloons at people, throw walking sticks at people, stuff keyholes with chewing gum and other such acts, simply for their amusement.

It is also strangely unknown how Poltergeists come about. They do not breed like most creatures and it does not seem normal for them to reproduce asexually. It is therefore likely that they are ancient and have existed since magic itself. For instance, Peeves haunts Hogwarts Castle since its creation.

Poltergeists typically haunt one specific location. It is unknown why this is so. When poltergeists choose a location to haunt, no one can get them out. They come with the location, so to speak. Despite this, the Minister for Magic can sign an order banning a poltergeist, as Dolores Umbridge once threatened Peeves, but the effectiveness of this is unknown.

Etymology
"Poltergeist" comes from the German, "Poltern", meaning "to make (loud) noise" and "Geist", meaning "Ghost" or "Spirit".

Notes and references
Esprit frappeur Полтергейст