ACIREALE (anc. ACIS), town and episcopal see, province of Catania, Sicily; 9m. N.E. from Catania by rail. Pop. (1931) 17,607 (town), 38,168 (commune). The thermal springs were used by the Romans. It took its name from the river Acis, into which Acis, the lover of Galatea, was changed after he had been slain by Polyphemus.