Aruch (Heb. Aruk', עָרוּך, arranged, sc. in alphabetical order), the title of a Talmudical lexicon, compiled by R. Nathan ben-Jechiel, who was rector of the synagogue at Rome A.D. 1106, according to the Chronicon " Zemach David," and who is usually styled by the Jewish writers בִּעִל עָרוּך, Auctor Aruch (Buxtorf, Lex Talm. col. 1605). It was first published by Soucini (Pesaro, 1517, fil.), and edited by Archinotti (Venice, 1531, 1533, fol.), Eckendorf (Basle, 1599, fol.), Musafia (Amst. 1655, fol.), and with Germ. notes by Landau (Prague, 1819-24, 5 vols. 8vo), also in Latin, by Kohut (Vien. 1878 sq;). See Furst, Bib. Jud. iii, 20 sq., Berlin, Additavmenta zum Aruch (Vien. 1830-59, 2 vols. 8vo).