TYCHSEN, OLAUS GERHARD° (Oluf Gerard; 1734–1815), Danish Orientalist. Born in Tönder, Schleswig, Tychsen is said to have learned Hebrew in Altona as a pupil of Jonathan *Eybeschuetz, and later to have studied rabbinics and Oriental languages at the University of Halle. After conducting unsuccessful missionary activities among Jews in Denmark and northern Germany (1759–60), he taught at the University of Buetzow in Mecklenburg (which subsequently became Rostock University), serving as professor of Oriental languages from 1763 until 1789.
Tychsen wrote on a variety of subjects, including the Bible, Hebrew coinage, and cuneiform inscriptions. He was a violent controversialist, and his views foreshadowed the German school of biblical criticism. His six-volume Buetzowische Nebenstunden (1766–69) reflects his Hebrew and rabbinic scholarship. He reputedly mastered Yiddish and also became an expert on Arabic and Syriac philology. His publications include Dialecti rabbinicae elementa (1763); De delectu veterum Ebraeorum (1763); De Pentateucho Ebraeo-Samaritano (1765); Abbreviaturarum Hebraicarum supplementum secundum (1769); an introduction to the Sefer Tikkunei Shetarot, on Jewish deeds of contract (1773); and De numis Hebraicis (1791).
F. Perez Bayer, Legitimidad de las monedas hebreo-samaritanas… (1793); A.T. Hartmann, Biblisch-asiatischer Wegweiser zu Oluf Gerhard Tychsen (1823); Steinschneider, Cat Bod 2687, no. 7321; Ḥ. Heller, Untersuchungen zur Septuaginta. vol. 1: Die Tychsen-Wutzsche Transkriptionstheorie (1932); Soncino-Blaetter, 2 (1927), 155.