IPA: /ˈwiːknaɪt/
KK: /ˈwikˌnaɪt/
A night that occurs during the week, typically from Monday to Friday, and not on the weekend.
We usually have family dinner on weeknights.
Weeknight → It is formed from "week" (from Old English *wice*, meaning a period of seven days) and "night" (from Old English *niht*, meaning the time of day when it is dark). The word "weeknight" refers to the nights that fall within a week, typically the nights from Sunday to Thursday.
Think of a 'week' as a period of seven days and 'night' as the dark time of day — together, they help you remember that a weeknight is simply a night during the week.