overconfidence

Excessive confidence; too great reliance or trust.

noun

The state or quality of being impudent or arrogantly self-confident: assumption, audaciousness, audacity, boldness, brashness, brazenness, cheek, cheekiness, chutzpah, discourtesy, disrespect, effrontery, face, familiarity, forwardness, gall¹, impertinence, impudence, impudency, incivility, insolence, nerve, nerviness, pertness, presumptuousness, pushiness, rudeness, sassiness, sauciness. Informal brass, crust, sauce, uppishness, uppityness. See attitude/good attitude/bad attitude/neutral attitude, courtesy/discourtesy.

The noun has one meaning:

Meaning #1: total certainty or greater certainty that circumstances warrant
  Synonyms: certitude, cocksureness