Real Dictionary

fluorescence in American English
the property of a substance, such as fluorite, of producing light while it is being acted upon by ultraviolet rays, X-rays, or other forms of radiant energy
noun: the emission of radiation, esp. of visible light, by a substance during exposure to external radiation, as light or x-rays

fluorescence in British English
noun: the emission of light or other radiation from atoms or molecules that are bombarded by particles, such as electrons, or by radiation from a separate source. The bombarding radiation produces excited atoms, molecules, or ions and these emit photons as they