in Mythology, the son of Faunus and the nymph Simethis, was a beautiful shepherd of Sicily, who being beloved by Galatea, Polyphemus the giant was so enraged, that he dashed out his brains against a rock; after which Galatea turned him into a river, which was called by his name.—The Sicilian authors say, that Acis was a king of this part of the island, who was slain by Polyphemus, one of the giants of Aetna, in a fit of jealousy.

a river of Sicily, celebrated by the poets, running from a very cold spring, in the woody and shady foot of Mount Aetna, for the space of a mile eastward into the sea, along green and pleasant banks, with the speed of an arrow, from which it takes its name. Its waters are now impregnated with sulphureous vapours, though formerly they were celebrated for their sweetness and salubrity, and were held sacred by the Sicilian shepherds.

Quique per Aetnaos Acis petit aquora fines, Et dulci gratam Nereida perluit unda. SIL. ITAL.

It is now called Il Fiume Freddo, Aci, Iaci, or Chiaci, according to the different Sicilian dialects: Antonine calls it Acius. It is also the name of a hamlet at the mouth of the Acis.