What word describes shining with less light?

The word that describes shining with less light is "dimmer." This term specifically refers to a reduction in brightness or illumination compared to something that is brighter. In various contexts, "dimmer" can apply to light sources that emit less intensity or glow, conveying the idea of a softer or subdued brightness.

Other options like "bright," "radiant," and "luminous" all suggest a higher degree of light or illumination. "Bright" typically denotes something that emits a strong amount of light. "Radiant" implies a powerful and vivid quality of light, often associated with warmth or brilliance. "Luminous" describes an object that emits light by itself or is exceptionally illuminated. None of these terms fit the description of reduced illumination as effectively as "dimmer" does.