The very link you cite says it is a continuous spectrum; the gamut of spectral colors: https://en.wikipedia.org/wiki/Spectral_color https://en.wikipedia.org/wik

The very link you cite says it is a continuous spectrum; the gamut of spectral colors: https://en.wikipedia.org/wiki/Spectral_color https://en.wikipedia.org/wiki/Spectral_color A "monochrome" rainbow is still a continuous decomposition of low temperature (warm) sunlight. A truly monochromatic "rainbow" requires a spectral light source.