The antonym for the word "more glimmering" could be "dull" or "dim." These words may imply a lack of shine or sparkle, and a sense of being deprived of light or luminosity. Another possible antonym could be "opaque," which suggests a lack of transparency, clarity, and brightness. Moreover, "gloomy" or "overcast" could be suitable antonyms for "more glimmering," as they denote dark, somber, or depressing conditions. Additionally, "shadowy," "murky," "obscure," or "nebulous" may serve as antonyms for "more glimmering," as they convey an absence of brightness, radiance, or vividness.