Cat·a·lo·nia (kāt'l-ōn'yə, -ō'nē-ə) A region of northeast Spain bordering on France and the Mediterranean Sea. In the late 19th and early 20th centuries it was a center of socialist and anarchist activity. Catalan separatists established an autonomous republic (1932-1938) that opposed Francisco Franco's loyalist forces during the Spanish Civil War (1936-1939). Cat'a·lo'nian adj. & n.