in (one's) day(redirected from in their days)
in (one's) day
When one was younger; in one's younger days. In my grandparents' day, planning a wedding wasn't such a colossal ordeal. Back in my day, the only thing we had to do for fun was stickball, and we were grateful for it!
in somebody’s day/time
1 when somebody was most successful, famous, etc: He had, in his day, been one of the greatest opera singers in the world.
2 at the time when somebody was alive; when somebody was young: In my grandmother’s time, women were expected to stay at home and look after the children. ♢ In my day, nobody would have spoken to the boss like that.
See also: time