the colour of light
When all the colours of the visible spectrum are combined, the result is white light. If this sounds odd, proof can be sought next time a rainbow appears in the sky. Water droplets in the air act as prisms and refract the white light generated by the sun revealing the individual wavelengths, which we know as rainbows. The same effect can be witnessed by shining white light onto any object able to act as a prism, such as a CD.
Black is omitted from the visible spectrum as black is not a colour wavelength in itself, but merely the absence of light