1820 as a shortening of quadrangle, n. in the building sense (in this case "quadrangle of a college," Oxford student slang); 1880 as short for quadrat, n.; 1896 as quadruplet, n., originally "bicycle for four riders;" later "one of four young at a single birth" (1951, of armadillos); 1970 as quadraphonic, adj.. Related: Quads.