a republic in NE Europe, on the Baltic Sea: a grand duchy in medieval times; united with Poland in 1569; occupied by Russia in 1795 and by Germany during World War I; independent Lithuania formed in 1918, but occupied by Soviet troops in 1919 and then by Poland; became a Soviet republic in 1940; unilaterally declared independence from the Soviet Union in 1990; recognized as independent in 1991; joined the EU in 2004. Official language: Lithuanian. Religion: Roman Catholic majority. Currency: euro. Capital: Vilnius. Pop: 2 890 297 (2017 est). Area: 65 200 sq km (25 174 sq miles)