Note 550 — BOOK VI. AN ACCOUNT OF COUNTRIES, NATIONS, SEAS, TOWNS, HAVENS, MOUNTAINS, RIVERS, DISTANCES, AND PEOPLES WHO NOW EXIST, OR FORMERLY EXISTED. (continued 2)
John Bostock translation
According to Bochart, this was a corruption of the Eastern name Deghel, from which were derived the forms Deger, Teger, and ultimately Tigris.