god of the infernal regions, the same with Pluto, so called from the Greek word ὀρχος, signifying a "tomb or sepulchre," or from ὀρχος "an oath by the river Styx." The ancients gave this name to all the divinities of the infernal regions, even to Cerberus. There was a river of the same name in Thessaly, which took its rise from the marshes of the Styx, and the waters of which were so thick that they floated like oil upon the surface of the river Peneus, into which they discharged themselves. This river probably suggested to the poets the idea of the infernal abodes, which they denominated Orcus. This deity has been confounded with Charon: he had a temple at Rome.