lu·​cif·​er·​in lü-ˈsi-f(ə-)rən How to pronounce luciferin (audio)
: any of various organic substances in luminescent organisms (such as fireflies) that upon oxidation produce a virtually heatless light

Did you know?

Luciferin got its name from the Latin word lucifer (meaning "light-bearing"), which is also a source of the word that is sometimes used as a name of the devil. We won't go into how Lucifer came to be called by that name-suffice it to say he wasn't always associated with darkness-but we will look a bit more closely at the Latin word lucifer. It comes from Latin luc-, meaning "light," plus -fer, meaning "bearing" or "producing." Additional relatives include the nontechnical adjective luciferous, meaning "bringing light or insight," and luciferase, the enzyme that catalyzes the oxidation of luciferin.

Examples of luciferin in a Sentence

Recent Examples on the Web Bioluminescence is believed to have evolved nearly 100 times across history, caused by a simple chemical reaction, when a light-producing molecule called a luciferin reacts with an enzyme called luciferase. Sam Jones, New York Times, 23 Apr. 2024 The process requires not only the synthesis of specialized chemicals like luciferin and luciferase but also the energy to fuel the light-producing reaction. Scott Travers, Forbes, 29 Feb. 2024 Bioluminescence is produced naturally when oxygen reacts with a substance called luciferin, with the help of an enzyme called luciferase, to produce energy in the form of light. WIRED, 19 Sep. 2023 Oxygen combines with chemicals called luciferin and luciferase to generate light with almost no heat. USA Today, 2 June 2023 For example, in order to do their glowing thing, fireflies use firefly luciferin or (4S)-2-(6-hydroxy-1,3-benzothiazol-2-yl)-4,5-dihydrothiazole-4-carboxylic acid, which looks like a ridiculously strong password. Bruce Y. Lee, Forbes, 3 Nov. 2021 Dumping firefly luciferin on plants is extremely expensive and can be toxic. John Timmer, Ars Technica, 30 Apr. 2020 The light is produced inside the tiny dinoflagellates body thanks to two chemicals: the enzyme luciferase and the compound luciferin. Stacey Leasca, Travel + Leisure, 27 Apr. 2020 Bioluminescence comes in a range of greens, reds and blues, and it’s caused by a protein called luciferin, often found in marine animals, mushrooms, insects, algae and specific types of bacteria. Jill Langlois, Smithsonian, 5 Dec. 2019

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'luciferin.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


International Scientific Vocabulary, from Latin lucifer light-bearing

First Known Use

1888, in the meaning defined above

Time Traveler
The first known use of luciferin was in 1888


Dictionary Entries Near luciferin

Cite this Entry

“Luciferin.” Dictionary, Merriam-Webster, Accessed 24 May. 2024.

Medical Definition


lu·​cif·​er·​in -(ə-)rən How to pronounce luciferin (audio)
: any of various organic substances in luminescent organisms that furnish practically heatless light in undergoing oxidation promoted by luciferase

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