noun (n)

• a hard smooth ivory colored dentine that makes up most of the tusks of elephants and walruses(noun.substance)

  Synonym:
  tusk
  

  source: wordnet30
• a shade of white the color of bleached bones(noun.attribute)

  Synonym:
  bone, off-white, pearl
  

  source: wordnet30
• The hard, white, opaque, fine-grained substance constituting the tusks of the elephant. It is a variety of dentine, characterized by the minuteness and close arrangement of the tubes, as also by their double flexure. It is used in manufacturing articles of ornament or utility.(noun)

  source: webster1913