DANU´BIUS(Δανούβιος: the Danube), on coins and inscriptions frequently called DANUVIUS,the greatest river in south-eastern Europe. Its sources are at Donaueschingen, on the Mons Abnoba, and, after a long course through Vindelicia, Noricum, Pannonia, and Dacia, it divides itself near Noviodunum into three main branches, so as to form a delta, and empties its waters into the Euxine. The Danube at first forms the southern frontier of Germania Magna; further east it is the boundary between Pannonia and Dacia, and between Dacia and Moesia. Among its many tributaries, we may mention the Dravus, Savus, Pathissus, and Margus, as the principal ones. This river was known even to the earliest Greeks, under the name of ISTER(Ἴστρος), though they knew only the part near its mouth, and entertained very erroneous notions respecting its course (Hesiod, Hes. Th. 338; Pind. O. 3.25; Aeschyl. ap. Schol. ad Apollon. Rhod. 4.284), which did not become fully known until the time of the Roman empire. The Romans, and especially their poets, sometimes adopted the Greek name ISTRUS or HISTER(Tibull. 4.1. 146), until in later, times the two names Ister and Danubius were used indiscriminately; though it was still very common to apply the former to the lower part of the river, and the latter to the upper part, from its sources to Vindobona or Sirmium. Stephanus B., who himself calls the river Danubis or Danusis, states that its ancient name was Matoas. It is said, moreover, that Danubius was its Thracian, and Ister its Celtic name (Lydus, De Mag. 3.32; Jornand. De Reb. Get. 12); but there can be no doubt that DAN is the same word which is found in Rhodanus, Eridanus, Tanais, Don, and others, and signifies water.According to Adelung, Dan-ubius means the upper water,and (Dan)-ister the lower water.The earlier writers entertained very vague and contradictory notions about the sources of this mighty river; thus Pindar makes it flow from the country of the Hyperboreans, Aeschylus from the Rhipaean mountains, Herodotus (Hdt. 2.33) from the country of the Celts in the extreme west (somewhere about the Pyrenees), and Scymnus of Chios ( Fragm. 31) likewise from the country of the Celts. Afterwards a notion arose that one branch of the Danube flowed into the Adriatic. But these and similar ideas, which were combated by some of the ancients themselves, were rectified during the conquests of the Romans in the north and east of Europe. We have already stated that there are three main branches by which the Danube empties itself into the sea; though Strabo appears to assume four, for out of the seven he mentions, he calls three the lesser ones. Other writers, however, mention only six, five, four, three, or even two mouths. The names of these mouths, so far as they are known to us, are:—(1) the southernmost, called Peuce or the sacrum ostium (τὸ ἱερὸν στόμα, Strab. 7. p. 305; Ptol. 3.10.2); (2) Naracustoma (Ναράκιονor τὸ Νάρακον, Ptol. 3.10.5; Arrian, Peripl. p. 23); (3) Calonstoma (τὸ καλὸν στόμα); (4) Pseudostoma (Ψευδόστομον, Ptol. 3.10.6); (5) Boreonstoma (Βόρειον στόμα, Ptol. l. c.); (6) Thiagola (Θιαγόλα, Ptol. 3.10.4, or τὸ ψιλὸν στόμα). Respecting these mouths, three of which were navigable in antiquity (P. Mela, 2.1, 8), see Kruse, De Istri Ostiis, Vratislav. 1820. At present it is impossible accurately to identify the statements of the ancients about them, as the Danube has undergone very great changes at its mouth. See Katancsich, De Istro, Budae, 1798, 4to.; Rennell, Comparative Geogr. of West. Asia, vol. 2. p. 374. [L.S]