Days of the week.

Days of the Week

Notice that "weekdays" and "days of the week" are not the same. "Days of the week" are all 7 days from Monday to Sunday. "Weekdays" are only the 5 days from Monday to Friday. The "weekend" is Saturday and Sunday.
Day Abbreviation
Monday Mon. Mo.
Tuesday Tue. Tu.
Wednesday Wed. We.
Thursday Thu. Th.
Friday Fri. Fr.
Saturday Sat. Sa.
Sunday Sun. Su.