As a Noun: 1. The brightness that lets you see things, and that comes from the sun, the moon, lamps, or fire. English = light. 2. Anything that produces light, particularly an electric bulb. English = light, electric light. As a Verb or Adjective: 1. To add brightness or light to a place by turning on anything that produces light, especially an electric bulb. English = light up, lighten, illuminate.