weekday

名词 weekday:

1. any day except Sunday (and sometimes except Saturday)

形容词 weekday:

1. occurring every day of the week except Sunday (and sometimes Saturday)

1. A newspaper published every day or every weekday.
   日报，周报每天或每周出版的报纸
2. The library is open on weekdays only.
   这个图书馆星期一至星期六都开放。
3. I don't stay out late on weekdays.
   工作日的时候我不在外面呆得很晚。

week.day

n.（名词）
Any day of the week except Sunday, or often except Saturday and Sunday.
周日：除了星期日或常指除了星期六和星期日的一周中的任一天
n.attributive.（定语名词）
Often used to modify another noun:
周日：常用来修饰其它名词：
例句：
weekday meetings; a weekday commute.
周日会议；周日上下班交通