To enlighten someone means to give them knowledge or understanding they didn't have before, especially about something important or complex. When a teacher enlightens students about how the solar system works, she's helping them see and understand something that was unclear or unknown to them.

The word suggests sharing meaningful understanding rather than random facts. When you enlighten someone, you're helping them understand something significant, like when a friend enlightens you about why a joke is funny, or when a documentary enlightens viewers about how coral reefs support ocean life.

The word comes from the idea of bringing light into darkness. Just as a lamp makes a dark room visible, enlightening someone makes a confusing topic clear. A science museum might enlighten visitors about electricity through hands-on exhibits. A biography might enlighten readers about what life was like in ancient Rome.

You can also ask someone to enlighten you when you want them to explain something: “Could you enlighten me about how this math problem works?” This shows you're genuinely curious and ready to learn.