Caucasus, theCau‧ca‧sus, the /ˈkɔːkəsəs/ (also Cau‧ca‧si‧a /kɔːˈkeɪziə $ -ˈkeɪʒə/)an area in the extreme south-east of Europe between the Black Sea and the Caspian Sea, which includes Russia, Georgia, Azerbaijan, and Armenia and contains the Caucasus Mountains