We do not currently know of any antonyms for Eastern Europe.
The proper noun Eastern Europe is defined as:
A socio-politic geographical area of eastern Europe usually including the European countries to the east of Germany, Austria and Italy, and to the west of the Urals. However, a less common definition of the region excludes the Czech Republic, Hungary, Poland, Slovakia, the Baltic states and some parts of the Balkans - placing them in Central Europe instead.
