adj. 25B6; adjective
his audacious exploits : BOLD, daring, fearless, intrepid, brave, courageous, valiant, heroic, plucky; daredevil, devil-may-care, death-or-glory, reckless, madcap; venturesome, mettlesome; informal gutsy, spunky, ballsy; poetic/literary temerarious.
an audacious remark : IMPUDENT, impertinent, insolent, presumptuous, cheeky, irreverent, discourteous, disrespectful, insubordinate, ill-mannered, unmannerly, rude, brazen, shameless, pert, defiant, cocky, bold (as brass); informal brass-necked, fresh, lippy, mouthy, saucy; N. Amer. informal sassy, nervy; archaic malapert, contumelious.
timid, polite.