Temerity
Etymology
From Latin temeritas, "rashness, heedlessness," from temere, "blindly, by chance, without reason." The root idea is acting in the dark — moving without looking, trusting to luck rather than judgment. That is precisely the flavor temerity retains: boldness uninformed by prudence.
noun · /tuh-MER-ih-tee/
Reckless boldness — a rash confidence that ignores danger or good sense.
What it names
The foolhardy nerve of someone who charges ahead heedless of the risk, where caution or humility was plainly called for.
Example
She had the temerity to correct the visiting expert on his own theorem — and, astonishingly, she was right.
Related idea
Audacity is daring that may be brave or even brilliant; temerity is daring that has tipped into folly — bold precisely where it should have paused.