CaucasusPronunciation: /ˈkɔːkəsəs/ (also Caucasia /kɔːˈkeɪzɪə, -ˈkeɪʒə/)Definition of Caucasus a mountainous region of SE Europe and SW Asia, lying between the Black Sea and the Caspian Sea, in Georgia, Armenia, Azerbaijan, and SE Russia. Caucasus in other Oxford dictionaries Definition of Caucasus in the US English dictionary