[floo-res-uh ns, flaw-, floh-]
See more synonyms for fluorescence on Thesaurus.com
noun Physics, Chemistry.
  1. the emission of radiation, especially of visible light, by a substance during exposure to external radiation, as light or x-rays.Compare phosphorescence(def 1).
  2. the property possessed by a substance capable of such emission.
  3. the radiation so produced.

Origin of fluorescence

1852; fluor(spar) + -escence, on the model of opalescence, in reference to the mineral's newly discovered property
Related formsnon·fluo·res·cence, noun
Can be confusedflorescence fluorescence
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Related Words for fluorescence

light, glow, brightness, luminance, fluorescence

Examples from the Web for fluorescence

Historical Examples of fluorescence

  • Phosphorescence is exhibited chiefly by solids, fluorescence also by liquids and vapors.

  • Fluorescence is most efficiently excited by the cathode rays of a vacuum tube.

  • We must conclude that animal light is not a fluorescence of any substance due to radiation produced by the animals themselves.

  • A trace of alkali usually increases and acid inhibits the fluorescence of solutions.

  • The ultraviolet rays falling upon this screen were transformed into visible rays by the phenomenon of fluorescence.

    Artificial Light

    M. Luckiesh

British Dictionary definitions for fluorescence


  1. physics
    1. 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 fall back to the ground state
    2. such an emission of photons that ceases as soon as the bombarding radiation is discontinued
    3. such an emission of photons for which the average lifetime of the excited atoms and molecules is less than about 10 –8 seconds
  2. the radiation emitted as a result of fluorescenceCompare phosphorescence

Word Origin for fluorescence

C19: fluor + -escence (as in opalescence)
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for fluorescence

1852, "glowing in ultraviolet light," coined by English mathematician and physicist Sir George G. Stokes (1819-1903) from fluorspar (see fluorine), because in it he first noticed the phenomenon, + -escence, on analogy of phosphorescence.

Online Etymology Dictionary, © 2010 Douglas Harper

fluorescence in Medicine


[flu-rĕsəns, flô-]
  1. The emission of electromagnetic radiation, especially of visible light, stimulated in a substance by the absorption of incident radiation and persisting only as long as the stimulating radiation is continued.
  2. The property of emitting such radiation.
Related formsfluo•rescent adj.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

fluorescence in Science


  1. The giving off of light by a substance when it is exposed to electromagnetic radiation, such as visible light or x-rays. As long as electromagnetic radiation continues to bombard the substance, electrons in the fluorescent material become excited but return very quickly to lower energy, giving off light, always of the same frequency. Fluorescent dyes are often used in microscopic imaging, where different dyes can penetrate and illuminate different parts of the sample being examined, helping to distinguish its structures. Compare phosphorescence.
  2. The light produced in this way.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

fluorescence in Culture


The emission of light from an object as a result of bombardment by other kinds of electromagnetic radiation, such as x-rays or ultraviolet rays. Fluorescent materials may appear one color when bathed in visible light and another color when exposed to other kinds of electromagnetic radiation.


“Black light” depends on fluorescence for its effects.
The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.