An Etymological Dictionary of the German Language/Annotated/Trotz
Trotz, masculine, ‘boldness, obstinacy, defiance,’ from Middle High German (Middle German) trotz, of which the more usual forms are Middle High German tratz, trutz, masculine, ‘refractoriness’; allied to Middle High German tratzen, tretzen, ‘to defy,’ tratz, ‘insolent, defiant, obstinate.’ The word is unknown to Old High German and the other Old Teutonic dialects, but there is no reason to suppose that it has been borrowed. —