An Etymological Dictionary of the German Language/Annotated/Kuppe
Kuppe, feminine, ‘peak, summit,’ adopted by the written language in the last century from Middle High German; in High German the form would have pf. Koppe and Kuppe, as well as Kaupe (‘crest of birds,’ also termed Koppe, compare Old Saxon coppod, ‘cristatus’ of snakes, under Kopf), are allied words, with the primary meaning ‘point, extreme end,’ which belonged originally to the strictly High German permutated form Kopf. The further history of all these terms is obscure; under Kopf it is assumed that they are of genuine Teutonic origin, though the possibility of their being blended with Middle Latin and Romance cupa, ‘beaker,’ is granted. In Middle High German kuppe, feminine Old High German chuppa, feminine, means ‘covering for the head’ (especially under the helmet); see Kopf.