means A type of ghost or supernatural force said to make its presence known through noise and physical mischief — banging, moving objects, and hurling things around — rather than appearing as a visible apparition.

from A German loanword, literally 'noisy ghost,' from poltern, 'to make a racket' or 'rumble,' plus Geist, 'spirit' (the same Geist you meet in Zeitgeist). English borrowed it in the 19th century, importing both the word and the idea of a spook whose calling card is clatter rather than a sheet in the hallway.