An Etymological Dictionary of the German Language/Annotated/Lilie
Lilie, feminine, ‘lily,’ from the equivalent Middle High German lilje, Old High German lilja, feminine; borrowed in Old High German from Latin lîlia, plural; the brevity of the i of the accented syllable in the German word and also in English (Anglo-Saxon lilie, English lily) is the same as in Linie and Litze, from Latin lînea and lîcium. Compare Rose.