An Etymological Dictionary of the German Language/Annotated/Tölpel
Tölpel, masculine, ‘blockhead, booby,’ from Middle High German törpel, dörpel, properly dörper, dörpœre, masculine, ‘peasant, clownish person, blockhead’; really identical with Dörfer, ‘villager.’ Middle High German dörper is a Middle German and Low German form (for genuine Middle High German dorfœre). The Low German form of the Middle High German word is explained by the fact that Flanders, the medium by which French terms relating to the court and chivalry were introduced into Germany, also furnished some words (compare Wappen) to High German.