any time, especially a time which is not usual or suitable :
He's started staying out till all hours (= until very late at night) .
She thinks she can call me at all hours of the day and night .
any time, especially a time which is not usual or suitable :
He's started staying out till all hours (= until very late at night) .
She thinks she can call me at all hours of the day and night .
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005