noun (n)

• the quality of being alike(noun.attribute)

  Example:
  Sameness of purpose kept them together.
  

  Antonym:
  difference
  

  source: wordnet30
• the quality of wearisome constancy, routine, and lack of variety(noun.attribute)

  Example:
  He hated the sameness of the food the college served.
  

  Synonym:
  humdrum, monotony
  

  source: wordnet30
• The state of being the same; identity; absence of difference; near resemblance; correspondence; similarity; as, a sameness of person, of manner, of sound, of appearance, and the like.(noun)

  source: webster1913