n. (Arch.) The central or topmost stone of an arch. This in some styles is made different in size from the other voussoirs, or projects, or is decorated with carving. See Illust. of Arch. [ 1913 Webster ]
. Pennsylvania; -- a nickname alluding to its having been the central one of the 13 original United States, at the time of formation of the Constitution. [ Webster 1913 Suppl. ]