The Collaborative International Dictionary of English v.0.48:

Audacity \Au*dac"i*ty\, n.
   1. Daring spirit, resolution, or confidence; venturesomeness.
      [1913 Webster]

            The freedom and audacity necessary in the commerce
            of men.                               --Tatler.
      [1913 Webster]

   2. Reckless daring; presumptuous impudence; -- implying a
      contempt of law or moral restraints.
      [1913 Webster]

            With the most arrogant audacity.      --Joye.
      [1913 Webster]

WordNet (r) 3.0 (2006):

audacity
    n 1: fearless daring [syn: audacity, audaciousness,
         temerity]
    2: aggressive boldness or unmitigated effrontery; "he had the
       audacity to question my decision" [syn: audacity,
       audaciousness]