Maybe that's a language issue, because purple and violet are color names around here. And as such, they are both a construct of the brain, as any other colors,

Maybe that's a language issue, because purple and violet are color names around here. And as such, they are both a construct of the brain, as any other colors, like... white. What we label as "violet wavelength" is only a narrow projection of our experience outward. Case in point, we don't have such colorful (eh) names for other EM wavelength. I say narrow because you could take this pure laser and change th surrounding and you will inevitably perceive it differently, even though the power and wavelength are the same.