from Wiktionary, Creative Commons Attribution/Share-Alike License.
- noun A person capable of identifying four primary colors, rather than three (
from Wiktionary, Creative Commons Attribution/Share-Alike License
And I think it's a bit difficult to know exactly how a non-human tetrachromat perceives light and color, though it's an intriguing possibility.
the difference being that you need two angles meaning that if you are tetrachromat, you have to consider a color "sphere" to describe hues, not a color "circle".