a region in SE Europe, S of the Caucasus Mountains, between the Black and Caspian seas: constituted a republic 1922–36 (Transcaucasian Socialist Federated Soviet Republic); area now includes the republics of Armenia, Azerbaijan, and Georgia.
Trans·cau·ca·sia (trāns'kô-kā'zhə, -zhē-ə, trānz'-) A region comprising present-day Georgia, Armenia, and Azerbaijan between the Caucasus Mountains and the borders of Turkey and Iran. Trans'cau·ca'sian adj. & n.