Pad can either refer to the bonding pad or the entire IO circuit.  The pad ring is the entire ring of IO circuits that goes around the chip.  If you're saying there's a pad ring in your pad circuit, I guess you might be referring to some metal that is used to link up adjacent pads and distribute vdd/gnd.  

There are also guard rings used for isolation of transistors and there's a seal ring that goes around the chip to mechanically stabilize it.