愚蠢 (yú chǔn): Stupid (Adjective) — Meaning & Stroke Order

He did a foolish thing.

Because of a stupid mistake, he failed the exam.

Not only did he not admit his mistake, but he also tried to cover it up; this is by no means wise and is utterly foolish.

I would never engage in such foolish behavior that harms others and does not benefit myself.

Giving up such a great opportunity is a really foolish decision.

Don't be silly; arguing over such a trivial matter is too foolish.