An adjective meaning slow, dull, or lacking intellectual ability; commonly used in everyday speech to criticize someone's mental quickness.
注意しても同じミスを繰り返すから、あの人は頭の悪いところがある。
He keeps making the same mistake despite being warned, so he can be a bit slow-minded.
頭の悪い決断をしてチームに迷惑をかけた。
I made a poor decision and caused trouble for the team.
子どもに『頭の悪い』と言うのは避けた方がいい。代わりにどう改善するか教えよう。
It's better to avoid telling a child 'you're stupid.' Instead, teach them how to improve.