Dictionary of Aramaic by R. Jacob Levy (1819–1892), rabbi and lexicographer. Born near Poznan, Poland, he studied under his father, Rabbi Isaac Levy, and under Rabbi Akiva Eger by whom he was ordained. He also studied philology and Middle Eastern languages at Breslau and Halle universities. For several years he served as rabbi of Rosenberg, Upper Silesia, but resigned from this post in 1850, in order to devote himself exclusively to scientific work. He settled in Breslau where he became assistant rabbi (dayyan) in 1857; in 1864 he was appointed to the Breslau court to administer the oathmore judaico ("Jewish Oath"). From 1878 to his death, he also served as lecturer at the Mora-Salomon Leipziger Foundation.

Levy's first major work was the Chaldaeisches Woer terbuch ueber die Targumim und einen grossen Teil des rabbinischen Schrifttums, 2 vols. (1867–68, 1881). For this work the Prussian government awarded him the title of "professor." A second monumental work, Neuhebraeisches und chaldaei sches Woerterbuch ueber die Talmudim und Midraschim (4 vols., 1876–89), is of particular importance because of the comparative study of its quotations: various versions from different manuscripts are given, explained, and translated. Both dictionaries were annotated by the Leipzig Arabist H.L. Fleischer. In 1924 the second of the two works was republished by L. Goldschmidt in a revised and enlarged version. Levy was the outstanding scholar of his time in the field of talmudic and rabbinical lexicography, and his successors, including Alexander Kohut , the author of Arukh ha-Shalem, based their scholarship on his work.