look up any word, like bae:
 
1.
The person who declares his victory without assessing his capabilities or the final result or situations.
Congress party in India was over-confident of its winning in Gujarat but Mr. Narendra Modi won after so much of critisism.
by deepa January 30, 2008
 
2.
Arrogant, presumptuous, assuming.
It's good to have a healthy self esteem, however being overconfident can wind you up in a corner.
by donyouknowtit January 13, 2010