The Latin-German »Vocabularis Ex quo« was, to judge from the more than 270 surviving manuscripts and some fifty incunabula editions, the most commonly used late medieval alphabetical dictionary on German soil. It was meant by its anonymous compiler-author to enable pauperes scolares to read and literally understand the Scriptures and other Latin texts. It dates from the late 14th century and, spreading all over the then German speaking countries, kept being copied until the last decades of the 15th century. During that very productive tradition it was subject to continuous change: almost every manuscript reveals different text. Yet, groups of manuscripts can be classified as descendants of nine major and most widely used revisions, eight of which are synoptically represented in the present edition. The text itself is accompanied by an introductory volume containing an up-to-date review of the research done on that subject, the lists of manuscripts and 15th century editions, an account of the überlieferungsgeschichtliche (K. Ruh) editorial principles, the classification of the text's tradition, and an alphabetical index of the more than 20.000 Latin entries.