Real Dictionary

white light
uncountable noun: White light is light such as sunlight that contains all the colors of the visible spectrum in roughly equal amounts.

white light in American English
light perceived by the eye as having the same color as sunlight at noon
light, as sunlight, that is a mixture of wavelengths ranging from red to violet

white light in British English
noun: light that contains all the wavelengths of visible light at approximately equal intensities, as in sunlight or the light from white-hot solids