noctilucent (adj) – emitting light or bioluminescence at night
BREAKDOWN: NOCT- (dark) + LUC- (light) + -ENT (full of)
— noctiluca are bioluminescent marine organisms
This word is built on the root LUC-, which means light, clear, and to shine.
Common LUC- words include translucent.
More esoteric LUC- words include lucent and lucubrate.