Thuringia (English: ; German: Thüringen [ˈtyːʁɪŋən] (listen)), officially the Free State of Thuringia (Freistaat Thüringen [ˈfʁaɪʃtaːt ˈtyːʁɪŋən]), is a state of central Germany, covering 16,171 square kilometres (6,244 sq mi), the sixth smallest of the sixteen German states. It has a population of about 2.1 million.

Erfurt is the capital and largest city. Other cities are Jena, Gera and Weimar. Thuringia is bordered by Bavaria, Hesse, Lower Saxony, Saxony-Anhalt, and Saxony. It has been known as "the green heart of Germany" (das grüne Herz Deutschlands) from the late 19th century due to its broad, dense forest. Most of Thuringia is in the Saale drainage basin, a left-bank tributary of the Elbe.

Thuringia is home to the Rennsteig, Germany's best-known hiking trail. Its winter resort of Oberhof makes it a well-equipped winter sports destination – half of Germany's 136 Winter Olympic gold medals had been won by Thuringian athletes as of 2014. Thuringia was favoured by or was the birthplace of three key intellectuals and leaders in the arts: Johann Sebastian Bach, Johann Wolfgang von Goethe, and Friedrich Schiller. The state has the University of Jena, the Ilmenau University of Technology, the University of Erfurt, and the Bauhaus University of Weimar.

Thuringia had an earlier existence as the Frankish Duchy of Thuringia, established around 631 AD by King Dagobert I. The state was established in 1920 as a state of the Weimar Republic from a merger of the Ernestine duchies, save for Saxe-Coburg. After World War II, Thuringia came under the Soviet occupation zone in Allied-occupied Germany, and its borders were reformed, to become contiguous. Thuringia became part of the German Democratic Republic in 1949 but was dissolved in 1952 during administrative reforms, to be divided into the Districts of Erfurt, Suhl and Gera. Thuringia was re-established in 1990 following German reunification, slightly re-drawn, and became one of the new states of the Federal Republic of Germany.