expression, godan verb (-tsu)
hold a grudge; bear resentment
Used when someone continues to feel resentment or ill will about a past event, often over a long period. The expression literally means 'to hold in the root', implying deep-seated feelings.
彼は小さな失敗を根に持つタイプだ。
He's the type who holds a grudge over small mistakes.
そんな昔のことをまだ根に持っている
Are you still holding that old thing against me?