1920, from French dada "hobbyhorse," child's nonsense word, selected 1916 by Romanian poet Tristan Tzara (1896-1963), leader of the movement, for its resemblance to meaningless babble.
Freedom: DADA DADA DADA, the howl of clashing colors, the intertwining of all contradictions, grotesqueries, trivialities: LIFE. [T. Tzara, "Dada Manifesto," 1918]