1. 
[syn: cocksure, overconfident, positive]
The Collaborative International Dictionary of English v.0.48:
Overconfident \O"ver*con"fi*dent\, a.
   Confident to excess. -- O"ver*con"fi*dent*ly, adv.
   [1913 Webster]
WordNet (r) 3.0 (2006):
overconfident
    adj 1: marked by excessive confidence; "an arrogant and cocksure
           materialist"; "so overconfident and impudent as to speak
           to the queen"; "the less he knows the more positive he
           gets" [syn: cocksure, overconfident, positive]
Moby Thesaurus II by Grady Ward, 1.0:
58 Moby Thesaurus words for "overconfident":
   arrogant, assured, audacious, brash, brazen, brazenfaced, cocksure,
   cocky, confident, convinced, decided, determined, foolhardy, hasty,
   heedless, hubristic, improvident, imprudent, impudent, incautious,
   indiscreet, injudicious, insolent, overbearing, overbold,
   overcareless, oversure, overweening, persuaded, poised, pompous,
   positive, presuming, proud, pushful, pushy, rash, reassured,
   secure, self-assertive, self-assured, self-confident,
   self-important, self-reliant, short-sighted, sure, swaggering,
   temerarious, thoughtless, unafraid, unchary, undoubting,
   unfaltering, unhesitating, unwary, unwavering, uppity,
   vainglorious