- a region in SE Europe, S of the Caucasus Mountains, between the Black and Caspian seas: constituted a republic 1922–36 (TranscaucasianSocialistFederatedSovietRepublic ); area now includes the republics of Armenia, Azerbaijan, and Georgia.
- a region in central Asia, south of the Caucasus Mountains between the Black and Caspian Seas in Georgia, Armenia, and Azerbaijan: a constituent republic of the Soviet Union from 1918 until 1936
