noun (n)

• the visual property of being without chromatic color(noun.attribute)

  Synonym:
  achromaticity, colorlessness, colourlessness
  Antonym:
  color, coloring, colour, colouring
  

  source: wordnet30
• The state or quality of being achromatic; as, the achromatism of a lens; achromaticity.(noun)

  source: webster1913