бытность

Жен. в бытность мою студентом — in my student days в бытность его в Риме — during his stay in Rome, in his Rome days в бытность — when, during someone's stay ж. : в мою ~ в Москве when I was staying/living in Moscow, during my stay in Moscow; в мою ~ студентом in my student days.

Источник: Полный русско-английский словарь на Gufo.me