More unilluminated is a term that describes something that is suffering from a lack of light, that which is dark and shadowy. Some suitable antonyms for this word could be light, bright, radiant, illuminated, and clear. If you want to convey the opposite of unilluminated, you could use words like brilliant, dazzling, glowing, or luminous. These words all describe something that is bathed in light and radiance and is far from being unilluminated. Using antonyms to contrast the negative quality of unilluminated with more positive ones that suggest lightness and brightness can create a vivid contrast in your writing.