Orion and ORUS, the names of several Greek grammarians, frequently confused. The following are the most important. (I) Orion of Thebes in Egypt (5th century A.D.), the teacher of Proclus the neo-Platonist and of Eudocia, the wife of the younger Theodosius. He taught at Alexandria, Caesarea in Cappadocia and Byzantium. He was the author of a partly extant etymological Lexicon (ed. F. W. Sturz, 1820), largely used by the compilers of the Etymologicum Magnum, the Etymologicum Gudianum and other similar works; a collection of maxims in three books, addressed to Eudocia, also ascribed to him by Suidas, still exists in a Warsaw MS. (2) Orus of Miletus, who, according to Ritschl, flourished not later than the 2nd century A.D., and was a contemporary of Herodian and a little junior to Phrynichus (according to Reitzenstein he was a contemporary of Orion). His chief works were treatises on orthography; on Atticisms, written in opposition to Phrynichus; on the names of nations.
See F. Ritschl, De Oro et Orione Commentatio (1834); R. Reitzenstein, Geschichte der griechischen Etymologika (1897); and article "Orion" in Smith's Dictionary of Greek and Roman Biography.