ACHELOUS, a river of Acarnania, which rises in Mount Pindus, and dividing Etolia from Acarnania, falls into the Ionian Sea. It was formerly called Thoas from its impetuosity, and king of rivers (Homer), being the largest in Greece. It has a course of 130 miles. The epithet Achelous is used for Aqueus (Virgil), the ancients calling all water Achelous, especially in oaths, vows, and sacrifices, according to Ephorus. It is now called Aspro Potamo. There was also a river in Arcadia, and another in Thessaly, of the same name.