Shiningness is a word that describes something that is bright and radiant. It can be used to describe anything that glows, sparkles, glistens, or shimmers. However, there are several antonyms for this word, which describe something that is dull or lackluster. Some of the antonyms for shiningness include darkness, dullness, murkiness, obscurity, and shadowiness. These words are the opposite of shiningness, and they can be used to describe anything that is dim, drab, or gloomy. So if you are looking for an antonym for shiningness, you can use any of these words to describe something that is not bright or radiant.