2.nounA period of seven days beginning with Sunday or Monday.
3.nounA period of five days beginning with Monday.
4.nounA subdivision of the month into longer periods of work days punctuated by shorter weekend periods of days for markets, rest, or religious observation such as a sabbath.
"A 4-day week consists of Monday, Tuesday, Wednesday, and Thursday."
5.nounSeven days after (sometimes before) a specified date.