As a Verb or Adjective: 1. To become less dark in colour. English = lighten. 2. Of a building or room, to have a lot of natural light in it, for example because it has large windows. English = (be) light. 3. Of colours, to be whitish and not strong or bright, as in 'light green' or 'pale green'. English = (be) light, (be) pale.