Etymology: Middle English weke, from Old English wicu, wucu; akin to Old High German wehha week and perhaps to Latin vicis change, alternation, Old High German wehsal exchange
Date: before 12th century
a. any of a series of 7-day cycles used in various calendars; especially a 7-day cycle beginning on Sunday and ending on Saturday
(1) a week beginning with a specified day or containing a specified holiday <Easter week> <the week of the 18th> (2) a week appointed for public recognition of some cause <Fire Prevention Week> 2. a. any seven consecutive days b. a series of regular working, business, or school days during each 7-day period 3. a time seven days before or after a specified day <last Sunday week>
New Collegiate Dictionary. 2001.