Dictionary.com (v 1.1) Random House Unabridged Dictionary Inc. 2006.
Date of origin: circa 1400 - 1450.
Boldness or daring, esp. with confident or arrogant disregard for personal
safety, conventional thought, or restrictions. Effrontery or insolence;
shameless boldness; "His questioner's audacity shocked the lecturer."
-Synonyms: nerve, spunk, grit, temerity, foolhardiness, impudence,
impertinence, or brashness.
-Antonyms: discretion, or prudence.
The American Heritage® Dictionary of the English Language, 4th Edition
Copyright © 2006 by Houghton Mifflin Company. All rights reserved
Fearless daring; intrepidity, bold or insolent heedlessness of restraints, as
of those imposed by prudence, propriety, or convention. An act or instance
of intrepidity or insolent heedlessness. "warned the students than any
audacities committed during the graduation ceremony would be punished."
Online Etymology Dictionary © 2001 by Douglas Harper
Boldness, brave, but more often "bold" in a bad sense; "to dare, be bold."
WordNet® 3.0, © 2006 by Princeton University
Fearless daring, aggressive boldness or unmitigated effrontery; "he had
the audacity to question my decision."