Another word from my cursed puzzle book that had me saying plenty of words that started with "eff" :-D
Effulgence seems like a word describing the output of a cow's rear end, but it actually is a dull word to describe radiant splendour. Who would have guessed? It even has a cousin that means the same thing, refulgence.
Please, please, don't use this word when you can use a more stellar descriptor such as brilliancy, lustre, splendor, luminous, brightness or radiance!