illuminant
radiation with a relative spectral power distribution defined over the wavelength range that influences object colour perception
Note 1 to entry: In everyday English, the meaning of the term "illuminant" is not restricted to this sense, but is also used for any kind of light falling on a body or scene.
Note 2 to entry: This entry was numbered 845-03-10 in IEC 60050-845:1987.
Note 3 to entry: This entry was numbered 17-554 in CIE S 017:2011.