balalaika (băl-ə-LĪ-kə) Definition (Noun) A musical instrument of the guitar kind, with a triangular body, popular in Russia and other Slav countries. In Context "Every new scene was accompanied by the ghastly twanging of a balalaika, a sound that gave the action a touch of the Devil." Anatoly Smeliansky, The Russian Theatre After Stalin, 1999.