| Term | Definition |
| luc | light |
| lum | light |
| illuminate | 1. to light up2. (abstract) - to make something complicated easier to understand3. (from medieval times) to decorate, especially a manuscript, with gold, silver, or bright colors, designs and pictures |
| lumens | a measurement of the brightness of light |
| bioluminescence | light produced by a living thing |
| luminary | someone who is a leader or is especially brilliant in their career |
| translucent | allowing light through, but usually not allowing clear vision through |
| lucid | 1. Clear and understandable2. A person is lucid if they can think reasonably clearly and make sense |
| luminist | painter who makes a specialty of the effects of light on colored objects |
| elucidate | to make something more clear |
| elucubrate | To think about and contemplate and work through until one understands |
| pellucid | 1. Letting light through completely and clearly. |