Return to spectrum (thing)

The visible Light Spectrum can be broken up into the following seven colours (yes I insist on spelling the word correctly!):

[Red], [Orange], [Yellow], [Green], [Blue], [Indigo], [Violet].

To get these colours one may refact light through a [prism], a glass window, a glass of water (etc) all held up to the light.

This can be explained most simply with the word [Rainbow].