Source : Webster's Revised Unabridged Dictionary (1913)

Acheron \Ach"e*ron\, n. [L., fr. Gr. ?.] (Myth.)
   A river in the Nether World or infernal regions; also, the
   infernal regions themselves. By some of the English poets it
   was supposed to be a flaming lake or gulf. --Shak.

Source : WordNet®

Acheron
     n : (Greek mythology) a river in Hades across which the souls of
         the dead were carried by Charon [syn: {River Acheron}]