Def: Rainbow

rain·bow  (rnb)

n.

1.a. An arc of spectral colors, usually identified as red, orange, yellow, green, blue, indigo, and violet, that appears in the sky opposite the sun as a result of the refractive dispersion of sunlight in drops of rain or mist.

b. A similar arc or band, as one produced by a prism or by iridescence.

c. A graded display of colors.

2. An illusory hope: chasing the rainbow of overnight success.

3. A diverse assortment or collection.

4. a term encompassing all the colors a child's poo can come in.