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

See Examples For:

fluorescence

The research team used fluorescence imaging to monitor how semaglutide affected living brain tissue from mice.

From Science Daily ● May 25, 2026

The water-soluble, FDA-approved dye used by UltraGreen.ai for fluorescence imaging is considered a generic drug and falls under the current exemption, they say.

From The Wall Street Journal ● Apr. 7, 2026

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

From BBC ● Feb. 9, 2026

These instruments measured fluorescence, which reflects energy released by phytoplankton when photosynthesis breaks down.

From Science Daily ● Jan. 12, 2026

As a Ph.D. student, he’d used HeLa to help develop something called fluorescence in situ hybridization, otherwise known as FISH, a technique for painting chromosomes with multicolored fluorescent dyes that shine bright under ultraviolet light.

From "The Immortal Life of Henrietta Lacks" by Rebecca Skloot