noun.
The emission of visible light by certain living organisms, such as the firefly and various fish, marine invertebrates, fungi, and bacteria. Bioluminescence is caused by chemical reactions.
the GNU version of the Collaborative International Dictionary of English
noun.
a type of luminescence produced by biological or biochemical processes, such as a glowworm glow or the action of luciferase on luciferin. A well-known example is that of firefly luminescence. See also luciferin.