What is "luciferin"

Luciferin \Lu*cif"er*in\ (l[=oo]*s[i^]f"[~e]r*[i^]n), n. (Biochem.) any of several substances found in luminescent organisms (such as the firefly, Photinus pyralis) which, when oxidized, produces an almost heatless light. It was first isolated from fireflies, and is the source of the firefly luminescence. See also firefly luciferin

n. (context biochemistry English) Any of a class of polycyclic heterocycles that are responsible for the bioluminescence of firefly, being converted to oxyluciferin by luciferase in the process.

n. pigment occurring in luminescent organisms (as fireflies); emits heatless light when undergoing oxidation

Luciferin (from the Latin lucifer, "light-bringer") is a generic term for the light-emitting compound found in organisms that generate bioluminescence. Luciferins typically undergo an enzyme-catalysed oxidation and the resulting excited state intermediate emits light upon decaying to its ground state. This may refer to molecules that are substrates for both luciferases and photoproteins.