na-adjective, noun
foolishness; stupidity; silliness
Describes a person, action, or idea as foolish, stupid, or lacking good sense. Often used in formal or written contexts.
彼の愚劣な行動には呆れてしまった。
I was appalled by his foolish behavior.
そんな愚劣な考えはすぐに捨てるべきだ。
You should discard such a stupid idea immediately.