Ok I checked the terminology and you're right, in Italian we call it "C natural" to distinguish it from the chord. Apparently in English you don't.
Also, in this way we can say "C major" or "C minor" to refer to the key of the song. We use "natural" when its important to distinguish from a note that has a sharp or flat - e.g. C# versus C natural.
In Italian, how would you refer to the key of Db major - "Db natural"? How would you refer to the key of Db minor?