Dictionary.net

Any one of several enzymes that catalyze the bioluminescent reaction in certain marine crustaceans, fish, bacteria, and insects. The enzyme is a flavoprotein; it oxidizes LUCIFERINS to an electronically excited compound that emits energy in the form of light. The color of light emitted varies with the organism. The firefly enzyme is a valuable reagent for measurement of ATP concentration. (Dorland, 27th ed) EC 1.13.12.-.

An oxidizing enzyme which acts on luciferine, causing luminosity in certain animals.

[Latin] An oxidising enzyme which acts on luciferin, causing luminescence; photogenin.