# fluorescence

/ˌfɫʊˈɹɛsəns/ (US) · /flɔːɹˈɛsəns/ (UK)

Source: https://englishreference.com/word/fluorescence
Updated: 2026-08-27

## Senses

### 1. the physical process

noun · CEFR C1 · Technical

the way some materials glow when they are hit by invisible energy like UV light.

For teachers: the physical phenomenon where a substance emits light immediately after absorbing electromagnetic radiation or subatomic particles.

- Scientists use fluorescence to see tiny structures inside cells under a microscope.
- The researcher observed the fluorescence of the mineral sample under ultraviolet light, noting the specific wavelengths emitted by the crystalline structure.

Usage: Often used as an uncountable noun when referring to the scientific principle.

### 2. the light emitted

noun · CEFR C1 · Technical

the actual light or glow that comes from a fluorescent object.

For teachers: the visible light or radiation produced during the process of fluorescence.

- The bright green fluorescence of the jellyfish made it easy to see in the dark water.
- The intensity of the fluorescence faded rapidly once the external radiation source was removed, confirming the material was not phosphorescent.

## Examples

- The rocks show a bright green fluorescence under UV light.
- Marine biologists use fluorescence to track the movement of certain jellyfish species in the dark ocean depths.
- In molecular biology, researchers attach fluorescent markers to specific proteins, allowing them to observe cellular processes through high-resolution fluorescence microscopy.

---

From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.