WordWeb Online

1. Invulnerable to fear or intimidation
   "audacious explorers";
   - brave, dauntless, fearless, hardy, intrepid, unfearing
    
2. Unrestrained by convention or propriety
   "an audacious trick to pull";
   - barefaced, bodacious [N. Amer, informal], bald-faced, brassy, brazen, brazen-faced, insolent
    
3. Disposed to venture or take risks
   "audacious visions of the total conquest of space"; "an audacious interpretation of two Jacobean dramas";
   - daring, venturesome, venturous

See also: adventuresome, adventurous, bold, unashamed

Encyclopedia: Audacious