noun (n)

• the amount of electromagnetic radiation leaving or arriving at a point on a surface(noun.phenomenon)

  Synonym:
  glow, glowing
  

  source: wordnet30
• the quality of being bright and sending out rays of light(noun.attribute)

  Synonym:
  effulgence, radiancy, refulgence, refulgency, shine
  

  source: wordnet30
• an attractive combination of good health and happiness(noun.state)

  Example:
  The radiance of her countenance.
  

  source: wordnet30
• The quality of being radiant; brilliancy; effulgence; vivid brightness; as, the radiance of the sun.(noun)

  source: webster1913