Friedrich Kluge, An Etymological Dictionary of the German Language (1891)
“ Compare Middle High German ze diute, ‘distinct, evident,’ and ‘in German’ (diute, dative singular of diuti, tiute, feminine, ‘exposition, explanation’) ; note too Anglo-Saxon geþeóde, ‘language’ (as the main characteristic of the nation) . deutsch, adjective, ‘German,’ from the equivalent Middle High German diutsch, tiutsch; the initial d of the Modern High German and Middle High German words is Middle German, the earlier form, teutsch (Middle High German tiutsch) , is Upper German, and was, especially by the UpGer. writers, constantly used till the end of the last century. ”
