A ring R is called a G-ring (or Grothendieck ring) if it is Noetherian and its formal fibers are geometrically regular; this means that for any p∈Spec(R), the map from the local ring Rp to its completion is regular in the sense above. One of Saturn's rings is named G ring. A ring, normally of stainless steel, bent to the shape of a "G". The ring is passed through a hole at the end of a pin or bolt to secure it from falling out. Used on sailing boats and yachts.