temerariousness

/tɛməˈrɛriəsnəs/
noun
  1. The quality of being recklessly bold or daring; foolish or rash courage.
    • The general warned that temerariousness in battle could get soldiers killed needlessly.
    • Her temerariousness in challenging the bully surprised everyone in the schoolyard.
    • The explorer's temerariousness led him into dangerous caves without proper equipment.