If intel sells a "3.2ghz cpu" and also advertises that it can run, thermals allowing, a core or two at 4.2ghz, I don't consider that 4.2ghz core "overclocked" as much as "this chip is engineered to have a variety of clocks as advertised." The chip is made from the factory to operate in a couple different ways, just like my car may have a transmission that allows the engine to spin at a couple different speeds, as duty cycle demand.

If I run the chip in a way not documented by the manufacturer, or modify the ECU to allow the turbo to generate more boost, those are both unsupported modifications, and I'd consider either of those "overclocking"