根据《牛津高阶英汉双解词典》(1989年第四版)，week 有以下几层意思：

1. period of seven days,usu reckoned from midnight on Saturday 星期，周（通常从星期六午夜算起）

last, next, this, etc week 上、下、本……星期

What day of the week was 2 July last year? 去年7月2日是星期几?

early next week 下周初

at the end of last week 上周末

Sunday is the first day of the week. 星期日是一个星期的第一天。

He comes to see us once a week. 他每星期来看我们一次。

2. any period of sevendays 七天的时间

a six weeks’ holiday 六周的假期

a week ago today, ie seven days ago 一星期前的今天

three weeks ago yesterday, ie twenty-two days ago 三周前的昨天

They are going on holiday for two weeks. 他们要度假两周。

I shall be away for no more than a week. 我离开不超过一个星期。

3. the six days apart fromSunday （除星期日以外的）六天

During the week, the road is very busy but there is very littletraffic on Sundays. 从星期一到星期六，这条路一直川流不息，但是星期日没什么车辆来往。

4. the five days otherthan Saturday and Sunday （除星期六和星期日以外的）五天

They live in Londonduring the week and go to the country at the weekend. 他们从星期一到星期五都住在伦敦，周末到郊外去。

They never have time to go to the cinema during the week. 他们从星期一到星期五从来都没有时间去看电影。

5. period in a week whenone works 一星期工作的时间

a 35-hour week 35小时的工作周

The government is introducing a shorter working week. 政府新采用减少每周工作时间的制度。

How many lessons are there in the school week? 学校里每星期有多少节课?