An Etymological Dictionary of the German Language/Annotated/Spuk
Spuk, masculine, ‘spectre, ghost,’ Modern High German only, properly a Low German word; it is unknown to Upper German (the strictly High German form Spuch occurs in early Modern High German); compare Low German and Dutch spook, from Teutonic spauka-. Allied to Swedish spok, ‘scarecrow,’ Danish spøg, ‘joke, fun,’ Norweg. spjok, ‘ghost’ (English spook is of Scandinavian origin). It is uncertain whether the word is related to Lithuanian spůgulas, ‘splendour.’