Sorry to labour the point BlueBonic, but I just disagree.
I don't think colour is subjective.
Again, going back to being faced with a myriad colour swatches. Are people even familiar with these?
There are blue tones of red, versus yellow tones of red. Blue greens, versus yellow greens. We all know what yellow looks like (unless colour blind), and so can recognise yellow-toned reds, blue-toned greys, green-toned greys, pink-toned whites, etc, etc.
We can recognise 'bright' colours, versus 'muted' colours - we can pick them out on a colour chart, and they will be the same as the next person who picks them out. Primary colours, secondary colours, tertiary colours. This is not a subjective thing.
A further example - paint companies grade colours by calling them 'xxxx colour', 'half xxxx', 'quarter xxxx', 'eighth xxxx'. We can all see the particular shade getting incrementally lighter. It's not subjective, unless you're colour blind.