temerity

Etymology

temer(arious) + -ity, from Middle English temerite, temeryte, from Old French temerité, from Latin temeritās (“chance, accident, rashness”), from temerē (“by chance, casually, rashly”).

noun

1. (uncountable) Reckless boldness; foolish bravery.
   1569, Thomas Pearson, trans., "The Second Paradox," in The booke of Marcus Tullius Cicero entituled Paradoxa Stoicorum, T. Marshe (London), Neyther the spightfull temerity and rashnes of variable fortune, nor the envious hart burning and in iurious hatred of mine enemies shold be able once to damnify me.
2. (countable) An act or case of reckless boldness.
   Draper, dear lad, had the illusion of an "intellectual sympathy" between them.... Draper's temerities would always be of that kind. 1910 Sept, Edith Wharton, “The Blond Beast”, in Scribner's Magazine, volume 48
3. (uncountable) Effrontery; impudence.
   He had very nearly been guilty of the temerity of arrogating to himself another title in the presence of those he most respected. 1820, James Fennimore Cooper, chapter 30, in Precaution
   That's jejune? You have the temerity to say that I'm talking to you out of jejunosity? I am one of the most june people in all of the Russias! 1975, Woody Allen, Love and Death, spoken by Boris (Woody Allen)