noun (n)

• freedom from doubt; belief in yourself and your abilities(noun.cognition)

  Synonym:
  assurance, authority, confidence, self-assurance, self-confidence
  

  source: wordnet30
• the quality of being steady and unfailing(noun.attribute)

  Example:
  Sureness of hand.
  

  source: wordnet30
• The state of being sure; certainty.(noun)

  source: webster1913