Answer :
Well, there's a very definite reason why a certain sliver of the electromagnetic
spectrum is called "visible".
The meaning of the word 'visible' is 'can be seen with eyes', and that's the label
given to the part of the electromagnetic spectrum that can be seen with eyes.
It doesn't include infrared or ultraviolet radiation, because those cannot be seen
with eyes. Only the 'visible' wavelengths can.
