\▐lü-mә-nәs\ adj [ME, fr. L luninosus, fr. lumin-, lumen] (15c) (1) Adjective used to imply dependence on the spectral response characteristic of the Standard Observer defined in the CIE System. Thus, the luminous reflectance or the luminous transmittance is described by the Y tristimulus value in the CIE System. The adjective is applied to many measures of light, such as intensity, density, etc., and always indicates the measures are weighted for the relative luminous sensitivity of the human observer. (2) Material emitting or spearing to be emitting, visible radiant energy.