An Etymological Dictionary of the German Language/Annotated/Kohl
Kohl, masculine. ‘cabbage,’ from the equivalent Middle High German and Old High German kôl, masculine, with the variants Old High German chôli, Middle High German kœle, kœl, masculine (compare Alemannian chœl, kêl), as well as Old High German chôlo, chŏlo, masculine, Middle High German kôle, kŏle, kŏl, and Old High German chôla, feminine. Adopted with the South European culinary art and horticulture from Latin caulis, masculine, ‘cabbage’; English cole; Middle English caul, coul, Anglo-Saxon câwl, as well as Old Icelandic kál, neuter, point to Latin caulis, whence also Italian cavolo, French chou, ‘cabbage,’ and Welsh cawl. The ‘apparently vernacular’ Latin côlis would have left no trace in the history of language if the Middle High German forms kŏle, kŏl, with a short accented syllable, were not derived from it. Most of the German varieties of fruits and vegetables may have been introduced into Germany with the art of cookery in the 6th or 7th century; compare Eppich, kochen, Pfeffer, Minze, Pflaume, and Kirsche.