Slovenia (Slovenija in Slovenian), country in south central Europe, bounded on the north by Austria, on the northeast by Hungary, on the southeast and south by Croatia, and on the west by Italy and the Adriatic Sea. Formerly a constituent republic of Yugoslavia, Slovenia proclaimed its independence in June 1991. It joined the United Nations (UN) in May 1992 and became a full member of the European Union (EU) in 2004. Slovenia has an area of 20,253 sq km (7,820 sq mi). Ljubljana is the capital and largest city.