An Etymological Dictionary of the German Language/Annotated/Zwetsche
Zwetsche, Quetsche, feminine, ‘damson’; Modern High German only; a difficult word to explain. Bavarian zwèšen, zwèšpen, Swiss zwetške, Austrian zwespen, Thuringian and East Middle German quatšge, seem to be related like quer and Zwerch, quängeln and zwingen, so that we must perhaps assume an initial tw. Since damsons were originally obtained from Damascus (the Crusaders are said to have introduced them into Europe; compare English damask plum, damascene, damson, Italian amascino, Portug. ameixa), it seems probable that the Teutonic cognates (Bavarian zwèschen) are derived from Middle Latin damascena or Greek δαμάσκηνον through the intermediate forms dmaskîn, dwaskîn, which appear in Transylvanian maschen, mäschen. Yet the phonological relations of the numerous dialectic forms are so indistinct that a final solution of all the difficulties has not yet been found. From High German are derived Dutch kwets, Danish svedske, Bohemian švetska.