"Without no sharp nor flat attached" - i.e. one of the white notes on the piano.

You only usually say 'natural' to stress that you don't mean sharp or flat - because, for example, if you refer to the note F when you're dealing in the key (scale) of G major - it would be taken to mean F sharp UNLESS you specifically said F natural.

It's the name of a note, not a of key (meaning a scale, really) - though it IS of course an actual key that you press down on the old joanna.

Very confusing, I do admit. Tom