Dictionary / Vocabulary / 経たぬうちに
たたぬうちに
before ... days (months, etc.)
Also written 経たぬ内に
外国へ行って1ヶ月も経たぬうちに、彼は病気になった。
He had not been abroad for one month before he was taken ill.
外国へ行って1ヶ月も経たぬうちに、トムは病気になった。
Within a month of going abroad, Tom became sick.