Light source refers to anything that produces light, such as a lamp or a candle. However, there are several synonyms for the term light source. One is illumination, which is the action of providing or casting light. Another synonym is luminosity, which is the quality of being bright and shining. A third synonym is radiance, which refers to the brightness and energy emitted from a light source. A forth synonym is beam, which is a focused stream of light. In summary, light source is a term that can be replaced with several synonyms, including illumination, luminosity, radiance, and beam.