expression, godan verb (-ru)
puzzle over; rack one's brains; think deeply about
Used when someone is struggling to solve a problem, come up with an idea, or understand something difficult. Often implies a visible effort of thinking.
難しい問題に頭を捻っている。
I'm racking my brains over a difficult problem.
彼はいいアイデアを出そうと頭
He puzzled over it, trying to come up with a good idea.