Wordnet 3.0
NOUN (1)
1. 
 freedom from doubt; 
 belief in yourself and your abilities; 
- Example: "his assurance in his superiority did not make him popular"- Example: "after that failure he lost his confidence"- Example: "she spoke with authority"[syn: assurance, self-assurance, confidence, self-confidence, authority, sureness]
WordNet (r) 3.0 (2006):
self-assurance
    n 1: freedom from doubt; belief in yourself and your abilities;
         "his assurance in his superiority did not make him
         popular"; "after that failure he lost his confidence"; "she
         spoke with authority" [syn: assurance, self-assurance,
         confidence, self-confidence, authority, sureness]