noun (n)

• an odd or unusual characteristic(noun.cognition)

  Synonym:
  distinctive feature, distinguishing characteristic
  

  source: wordnet30
• a distinguishing trait(noun.attribute)

  Synonym:
  distinctiveness, speciality, specialness, specialty
  

  source: wordnet30
• something unusual -- perhaps worthy of collecting(noun.artifact)

  Synonym:
  curio, curiosity, oddity, oddment, rarity
  

  source: wordnet30
• The quality or state of being peculiar; individuality; singularity.(noun)

  source: webster1913