Illuminated means lit up or made bright with light. When you flip a light switch, the room becomes illuminated. A flashlight illuminates a dark path through the woods. The full moon illuminates the night sky, making it possible to see without artificial lights.

When something is illuminated, light reveals details you couldn't see before. A museum might use special lamps to illuminate an ancient sculpture, showing the fine craftsmanship. Scientists illuminate specimens under microscopes to study them closely.

The word also describes a special kind of decorated manuscript from medieval times. An illuminated manuscript was a handwritten book decorated with gold, silver, and brilliant colors. Monks spent years creating these magnificent books, painting elaborate borders, ornate letters, and detailed illustrations. These books literally glowed with metallic inks that caught and reflected light. Today, museums treasure these books as masterpieces of art and patience.

You can also use illuminate figuratively to mean making something clear or easier to understand. A good teacher illuminates difficult concepts, shedding light on confusing ideas. When you suddenly understand something tricky, you might say, “That really illuminates the problem.”