An Etymological Dictionary of the German Language/Annotated/Nacken
Nacken, masculine, ‘nape,’ from Middle High German nacke, nac (genitive -ckes), masculine, ‘hind part of the head, nape,’ Old High German nac hnac (cch), masculine; compare Dutch nek, Anglo-Saxon hnëcca, masculine, ‘neck, nape,’ English neck, Old Icelandic hnakke, masculine, ‘hind part of the head’ (Gothic *hnakka, *hnikka, is wanting). In Suabian and Franconian Anfe or Genick is mostly used, and in Bavarian Genäck (the Bavarian meaning of nacken, ‘bone,’ is remarkable). The graded form with ë (Anglo-Saxon hnëcca) parallel to a-o is preserved by Modern High German in Genick; English nape (Anglo-Saxon hnapa?) seems to be a corresponding form with a medial labial. In the non-Teutonic languages the word may be cognate with Old Irish cnocc, OBret. cnoch, ‘hill, elevation’ (stem cnocco-).