fluorescence

American  

[floo-res-uhns, flaw-, floh-] / flʊˈrɛs əns, flɔ-, floʊ- /

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.

2. the property possessed by a substance capable of such emission.

3. the radiation so produced.

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fluorescence British  

/ ˌflʊəˈrɛsəns /

noun

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 fluorescence Compare phosphorescence

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fluorescence Cultural  

1. 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.

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Discover More

“Black light” depends on fluorescence for its effects.

Other Word Forms

• nonfluorescence noun

Etymology

Origin of fluorescence

1852; fluor(spar) + -escence, on the model of opalescence ( def. ), in reference to the mineral's newly discovered property

Example Sentences

Emerging portable testing methods include X-ray fluorescence analysers for turmeric and handheld DNA kits to test olive oil.

From BBC • Feb. 9, 2026

"In the way fluorescence works, you shine light beams at something, and you get a different wavelength of light beams back," said Moore, who directs the Bioluminescence Hub.

From Science Daily • Dec. 19, 2025

“Radioactive decay does not typically produce visible fluorescence, so, no,” wrote Megan Cook of the Australian Radiation Protection and Nuclear Safety Agency in an email.

From Slate • Aug. 21, 2025

Machine-learning-driven algorithms detangled the fluorescence signals from one another, providing an easy readout of each biomarker.

From Science Daily • Dec. 4, 2024

In the daytime, the hospital was a maze of teeming, angled hallways, a blur of blazing-white overhead fluorescence.

From "The Kite Runner" by Khaled Hosseini