上の空

absent-minded

→ 上
phrase Rare #41,296
absent-minded An idiomatic expression for being distracted or not paying attention because one's mind is elsewhere.
JA: 授業中、彼女はずっと上の空だった。
EN: She was absent-minded throughout class.

上の空話を聞いてたでしょう

You weren't really listening, were you?

明らかに上の空よね

You're obviously distracted, aren't you?

彼は上の空

He's absent-minded.

上の空でした

It was empty upstairs.

— オッペンハイマー (2023)