| n. | 1. | (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 |
| Noun | 1. | luciferin - pigment occurring in luminescent organisms (as fireflies); emits heatless light when undergoing oxidation |