Prussia ( or Preussen) can mean:
Old Prussia, the historic land of the Baltic Old Prussians
Prussia (region), a region named after Old Prussia
Prussian Confederation, an alliance of German Hanseatic cities in Prussia who rebelled against the Teutonic Knights
Royal Prussia, a province of the Polish Crown, created by separating Prussia into two parts in 1466
Duchy of Prussia, a duchy established in the eastern part of Prussia in 1525
Preussen (ship), the largest sailing vessel ever built
Prussia, a former German state originating in Brandenburg-Prussia
Brandenburg-Prussia, a state created by the personal union of the Duchy of Prussia and the Margraviate of Brandenburg
Kingdom of Prussia, a kingdom established in Brandenburg-Prussia (1701-1918)
West Prussia, a province of the Kingdom of Prussia, annexed from Poland in 1772 (former Royal Prussia)
East Prussia, a province of the Kingdom of Prussia, created by uniting former Ducal Prussia and Warmia in 1773
Province of Prussia, a province of the Kingdom of Prussia, created by uniting East and West Prussia (1824/29-1878)
Free State of Prussia, a state in Germany (1918-1945) after the abolition of the Kingdom of Prussia
Posen-West Prussia, a province of the Free State of Prussia (1922-1938) (part of former West Prussia which stayed with Germany)
West Prussia (district), western district of the province of East Prussia (1920-1938) (the other rest of former West Prussia)
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