Rainbow n. : A bow or arch exhibiting, in concentric bands, the several colors of the spectrum, and formed in the part of the hemisphere opposite to the sun by the refraction and reflection of the sun's rays in drops of falling rain.

Example:
Does Rainbow trout have the same nutritional values as salmon?

Taxonomy
rainbow, colours, bow, raindrop, reflection, Hex, RGB, violet, colours of the rainbow, arc, sun, Supernumerary, sky, clouds, rays, explanation, droplet, secondary rainbow.

Defination from the web:
rainbow circle (antisolar point). A rainbow is an optical and meteorological phenomenon that causes a spectrum of light to appear in the sky when the Sun shines onto droplets of ...