An Etymological Dictionary of the German Language/Annotated/Lauch
Lauch, masculine, ‘leek, garlic,’ from. the equivalent Middle High German louch, Old High German louh(hh), masculine; compare the corresponding Old Icelandic laukr, Dutch look, Anglo-Saxon leác, English leek, with which lic in garlic is connected; a primitive and common Teutonic word, which was adopted in Finnish as laukka and in Old Slovenian as lukŭ. Like most of the old names of plants and animals, it is of obscure origin. Greek λύγος, ‘a pliant rod or twig for wicker-work, willow-like tree,’ cannot be allied on account of its meaning. Perhaps Old Irish luss, ‘herb, plant’ (from *luksu-), is a cognate.