(n.) Excessive confidence; too great reliance or trust.

arrogance assurance assuredness belief brashness brass brazen boldness certitude cheek chutzpah cocksureness confidence confidentness conviction courage faith gall heroics hubris improvidence imprudence impudence indiscretion injudiciousness insolence overboldness overcarelessness oversureness overweening overweeningness poise pomposity positiveness pride rashness security self-assurance self-confidence self-importance self-reliance settled belief subjective certainty sureness surety temerariousness temerity trust unchariness unwariness