ACHELOUS, ăk'ḗ-lō'ŭs (Gk. Ἀχελῷος, Achelōos, now called Aspropotamos, i.e., White River, from the cream color of its waters). The largest river in Greece (Map: Greece, C 5). It rises in Mount Pindus, flows southward, separating Ætolia from Acarnania, and falls into the Ionian Sea. It is over 100 miles long, and unnavigable.