afterglow vs illuminant

afterglow

• The light emitted by an incandescent object while cooling. 

• The mildly euphoric feeling experienced after a pleasurable experience, especially after an orgasm or drug-induced high. 

• An afterparty. 

• The glow seen in the sky after sunset. 

• The light emitted by a phosphor after excitation. 

illuminant

• Something that illuminates. 

• That illuminates.