noun (n)

• the location of a visual perception along a continuum from black to white(noun.attribute)

  Antonym:
  dullness
  

  source: wordnet30
• intelligence as manifested in being quick and witty(noun.cognition)

  Synonym:
  cleverness, smartness
  

  source: wordnet30
• the quality of being luminous; emitting or reflecting light(noun.attribute)

  Synonym:
  brightness level, light, luminance, luminosity, luminousness
  

  source: wordnet30
• The quality or state of being bright; splendor; luster; brilliancy; clearness.(noun)

  source: webster1913