Insufficient preparation; the state of being not adequately prepared for something.
彼の発表は準備不足で、質問にほとんど答えられなかった。
His presentation was poorly prepared and he couldn't answer most of the questions.
準備不足が原因でプロジェクトは予定通り進まなかった。
The project did not proceed as planned because of insufficient preparation.
試合に備えてもっと練習すべきだ。今は準備不足だ。
You should practice more for the match. Right now you're not well prepared.