Achaea definition by Webster's New World
Achaea definition by American Heritage Dictionary
An ancient region of southern Greece occupying the northern part of the Peloponnesus on the Gulf of Corinth. The cities of the region banded together in the early third century B.C. to form the Achaean League, which defeated Sparta but was eventually beaten by the Romans, who annexed Achaea in 146 B.C. and later gave the name to a province that included all of Greece south of Thessaly.