A pointed arch based on four circular arcs.; 
A flattened arch with a center point above a door or window, commonly seen in Tudor Revival style buildings, (also called a 4 centered arch).
[n] - a low elliptical or pointed arch
four-centered arch noun a low elliptical or pointed arch; usually drawn from four centers
a four-centered arch, the inner pair of curves having a radius much greater than that of the outer pair. See illus. under