week

Definition:

The term "week" literally refers to a period of time lasting seven days.

In the Jewish system of counting time, a week begins at sunset on Saturday and ends at sunset the following Saturday.
In the Bible, the term "week" is sometimes used figuratively to refer to a group of seven units of time, such as seven years.
The "Festival of Weeks" is a celebration of harvest that takes place seven weeks after Passover. It is also called "Pentecost."