muumuu (n.)

also muu-muu, "loose-fitting dress, usually of bright colors and patterns," 1923, from Hawaiian mu'u mu'u, literally "cut off," name given to the local adaptation of the dresses given to island women by the wives of early 19c. Christian missionaries "in the early days when a few flowers sufficed for a garment" [Don Blanding, "Hula Moons," 1930]. So called because the native style hangs from the shoulder and omits the high neck and the train.