2.The planet Venus, when appearing as the morning star; Lucifer. (Poetic and Rare)
3.A phosphorescent substance. (archaic)
4.A substance capable of exhibiting luminescence. This term is now most commonly used to refer to substances used in fluorescent lights, image intensifiers, or cathode-ray tubes (CRT's), which luminesce when excited by ultraviolet radiation or an electron beam. In color CRT's, three different phosphors, each giving different colors when excited, are used.
