The antonyms for the word "un-illuminated" are illuminated, brightened, lit, lighted, enlightened, glowing, and radiating. Each of these signifies a state of lightness, brightness, or warmth that opposes the dull, dark, or shadowy feeling of un-illuminated. For instance, "illuminated" means to brighten or light up whereas "brightened" relates to increasing the intensity of the light. "Lit" implies a place or object is lit up by fire or electricity, while "lighted" refers to something being made lighter by illuminating it. "Enlightened" denotes a state of understanding or knowledge that brings light to a formerly obscure topic or area.