Magna GraeciaPronunciation: /ˌmagnə ˈgriːsɪə, ˈgriːʃə/Definition of Magna Graecia the ancient Greek cities of southern Italy, founded from circa 750 bc onwards by colonists from Euboea, Sparta, and elsewhere in Greece. Origin:Latin, literally 'Great Greece'Magna Graecia in other Oxford dictionaries Definition of Magna Graecia in the US English dictionary