Foolhardiness is the quality of taking stupid, unnecessary risks — being brave in a way that is not wise. A foolhardy person is not simply afraid of nothing; they rush in when a careful person would wait, prepare, or stay back. Climbing a wet roof to get a ball, driving far too fast, walking into danger to look brave: that is the idea. It is not a compliment. Courage looks at the danger and still has a reason; foolhardiness skips the reason. The everyday word is the adjective foolhardy. The noun foolhardiness is more formal, the sort of word a report or a teacher might use. People rarely say it about a small mistake; they save it for a risk that could really hurt someone.