The term "lumination" refers to the act of lighting or illuminating something. Antonyms for this word might include "darkness," "shadow," "gloom," "obscurity," or "dimness." Essentially, any word that describes the absence of light or brightness could be considered an antonym of "lumination." Other possible antonyms might include "opacity," "murkiness," "dullness," "grayness," or "dimming," as all of these words describe a lack of clarity, brightness, or illumination. While "lumination" itself might not be a particularly common word, its antonyms are widely recognized and useful for describing a wide range of situations where light is absent or limited.