D defs.my
Entry 4 senses Webster, 1913

Phosphor

/(fŏs"fôr or fŏs"fŏr)/ · Phos·phor · IPA /ˈfɑsfɚ/
01 n. Phosphorus.
  1. 1.
    Phosphorus.[Obs.]
  2. 2.
    The planet Venus, when appearing as the morning star; Lucifer.[Poetic and Rare]
  3. 3.
    A phosphorescent substance.[archaic]
  4. 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.