An Etymological Dictionary of the German Language/Annotated/Kröte
Kröte, feminine, from the equivalent Middle High German krote, kröte, krëte, feminine (even now dialectic Krote, Krotte), Old High German chrota, chrëta, feminine, ‘toad.’ The forms with ë and o are related by gradation; compare Brett and Bord. The word is peculiar to German; in Old Icelandic padda, Dutch padde, Anglo-Saxon tâdie, English toad. Etymologically all three are equally obscure.