1. [n]  a river in ancient Thrace (now Turkey); in the mouth of this river the Spartan fleet under Lysander destroyed the Athenian fleet in the final battle of the Peloponnesian War (404 BC)
2. [n]  a creek emptying into the Hellespont in present-day Turkey; at its mouth in 405 BC the Spartan fleet under Lysander defeated the Athenians and ended the Peloponnesian War

AEGOSPOTAMOS is a 12 letter word that starts with A.