Why is the ninth month called September?
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.
[said to be a shortening of quadrilateral, ''square'']
A set of four headlights on a car (1950s+ Hot rodders)