Audacious means daringly bold, sometimes to the point of being shocking or disrespectful. An audacious person takes big risks that others might think are reckless or impudent.

When the Wright brothers tried to build a flying machine, people called their dream audacious because everyone “knew” humans couldn't fly. Their bold idea seemed outrageous, but it worked. That's audacious in a positive sense: courageously tackling something that seems impossible.

But audacious can also describe behavior that crosses a line. If a student talks back to the principal or walks into the teacher's lounge like they own the place, that's audacious too: bold in a way that shows a lack of respect for normal boundaries.

The word captures that electric moment when someone does something so bold you're not sure whether to admire their courage or gasp at their nerve. An audacious plan might be brilliant or foolish, and sometimes you only know which one after you see how it turns out. When someone calls an idea audacious, they're acknowledging both its boldness and the real possibility it might fail spectacularly.