A colour is essentially the property of or possessed by an object that produces different sensations visually or simply put, sensations on the eye resulting from the way it reflects or emits light.
The question was asked, are we sure the leaf of a tree is green? Obviously we know it's green and not all trees have green leaves, but know this truth, there is a difference between perceived light and how we perceive colour. However, lets not venture into philosophy today, science has the answer to the practical.
How we perceive the colour of an object depends on a few things:
- The range of wavelengths present in the incident light.
- The wavelengths of light that the object reflects or absorbs.
- The receptor cells in our eyes that detect the reflected light.
- Our brain’s interpretation of the signals from those receptors.
Colour is often categorized or labeled base don our brain's interpretation than light or the actual object itself.