A week is a time unit equal to seven days.

The English word week continues an Old English wice, ultimately from a Common Germanic *wikōn-, from a root *wik- "turn, move, change". The Germanic word probably had a wider meaning prior to the adoption of the Roman calendar, perhaps "succession series", as suggested by Gothic wikō translating taxis "order" in Luke 1:8.

The term "week" is sometimes expanded to refer to other time units comprising a few days. Such "weeks" of between four and ten days have been used historically in various places.[1] Intervals longer than 10 days are not usually termed "weeks" as they are closer in length to the fortnight or the month than to the seven-day week.


Seven-day week

Evidence of continuous use of a seven-day week appears with the Jews during the Babylonian Captivity of the 6th century BC.[2] Both Judaism (based on the Creation narrative in the Torah/Bible) and ancient Babylonian religions used a seven-day week.[3] Other cultures adopted the seven-day week at different times. Between the 1st and 3rd centuries the Roman Empire gradually replaced the eight-day Roman nundinal cycle with the seven-day week. The seven day week begins on a Monday.[4] Hindus may have adopted a seven day week earlier than 11th century BC.[citation needed] See Rig Veda. There is evidence of some Chinese groups using a seven day week as early as 4th century AD.

Systems derived from the seven-day week

Soviet Union

Soviet calendar
12 December 1937
(Below 12:)
"Sixth day of the six-day week"
"Election day for the Supreme Soviet of the USSR"

Between 1929 and 1931 the USSR changed from the seven-day week to a five-day week. There were 72 weeks and an additional five national holidays inserted within three of them totaling a year of 365 days.[citation needed]

In 1931, after its brief experiment with a five-day week, the Soviet Union changed to a six-day week. Every sixth day (6th, 12th, 18th, 24th and 30th) of the Gregorian Calendar was a state rest day. The five additional national holidays in the earlier five-day week remained and did not fall on the state rest day. But as January, March, May, July, August, October and December have 31 days, the week after the state rest day of the 30th was seven days long (31st–7th). This extra day was a working day for most or an extra holiday for others. Also as February is only 28 or 29 days depending on whether it is a leap year or not, the first of March was also made a state rest day, although not every enterprise conformed to this. To clarify, the week after the state rest day, 24/25 February to 1 March, was only five or six days long, depending on whether it was a leap year or not. The week after that, 2 to 6 March, was only five days long.[citation needed]

The calendar was abandoned 26 June 1940 and the seven-day week reintroduced the next day.[citation needed]

Decimal calendar

A 10-day week, called décade, was used in France for nine and a half years from October 1793 to April 1802; furthermore, the Paris Commune adopted the Revolutionary Calendar for 18 days in 1871.

Christian "eighth day"

For early Christians, Sunday, as well as being the first day of the week, was also the spiritual eighth day, as it symbolised the new world created after Christ's resurrection. The concept of the eighth day was symbolic only and had no effect on the use of the seven-day week for calendar purposes. Justin Martyr wrote: "the first day after the Sabbath, remaining the first of all the days, is called, however, the eighth, according to the number of all the days of the cycle, and [yet] remains the first".[5] This does not set up an eight-day week, since the eighth day is also considered to be the first day of the next cycle (i.e., not the following day).

A period of eight days, starting and ending on a Sunday or starting on a major feast day and finishing on the same day of the week a (seven-day) week later, is called an octave. For centuries these were a major feature of the liturgical calendar, particularly of the Catholic Church, and some are still observed, though the number of such octaves has now been radically reduced. Some modern Church uses also preserve the idea of an eight-day period, starting and finishing on the same day of the week, and retain the name "octave" for them; for example, many churches observe an annual "Octave of Prayer for Christian Unity" on 18–25 January or in the week that begins with Pentecost Sunday. Organizations such as 8th Day Center for Justice, based out of Chicago, Illinois, use the concept in terms of social justice as well.

Hermetic lunar week

The Hermetic Lunar Week Calendar is one of many proposed reforms to the Gregorian Calendar. The lunation is divided into the four moon phases and has six, seven, eight, or nine days depending on the actual time difference between the full moon, first quarter, new moon and last quarter.[6]

"Weeks" in other calendars

Periods termed "weeks" in calendars unrelated to the Judeo-Christian tradition.

Three day

The names of the days of the week (aste) in Guipuscoan Basque point to an earlier three-day week.[7]

  1. astelehena ("week-first", Monday)
  2. asteartea ("week-between", Tuesday)
  3. asteazkena ("week-last", Wednesday)


The Igbo of Nigeria have a traditional calendar with a four-day week. This "market week" features prominently in the fiction of Chinua Achebe.


The Javanese people of Indonesia have a five-day week known as the Pasaran cycle. This is still in use today and superimposed with seven-day week of the Gregorian calendar and Islamic calendar to become what is known as the 35-day Wetonan Cycle.


The Akan people of West Africa have a 42-day cycle known as Adaduanan. The Adaduanan cycle appears to be based on an older six-day week, still existent in some northern Guan communities such as the Nchumuru, on which is superimposed a seven-day week which may have been brought south with itinerant traders from the Savannah.[8] The six-day week is referred to as Nanson (literally seven-days) and reflects the lack of zero in the numbering systems; the last day and the first day are both included when counting the days of a week.


Nundinal cycle

The ancient Etruscans developed an eight-day market week known as the nundinal cycle around the 8th or 7th century BC. This was passed on to the Romans no later than the 6th century BC. As Rome expanded, it encountered the seven-day week and for a time attempted to include both. The popularity of the seven-day rhythm won and the eight-day week disappeared forever.

The cycle of seven days, named after the sun, the moon, and the five planets visible to the naked eye, was already customary in the time of Justin Martyr, who wrote of the Christians meeting on the Day of the Sun (Sunday).[9]

Emperor Constantine eventually established the seven-day week in the Roman calendar in AD 321.[10]


It is believed the ancient celts of the British Isles used a nine-night week. The moon was used to measure one day from another so nights were more significant. The nine nights divided nicely into a sidereal month of 27 nights. Each week of nine nights had eight days.[11]


The Gediminas Sceptre, a medieval Lithuanian calendar. Showing 12 months and 9 days in a week

Baltic calendars

In the 14th century, the Grand Duchy of Lithuania used a solar-lunar calendar. The structure of this calendar was understood with the help of the so-called Gediminas Sceptre discovered in 1680.[12]

Historical records[citation needed]give evidence that the week of the ancient Balts was nine days long. Thus, the sidereal month must have been divided into three parts.[13]



The Chinese ten-day week went as far back as the Shang Dynasty (1200-1045 BC).[14] The law in the Han Dynasty (206 BC – AD 220) required officials of the empire to rest every five days, called mu (沐), while it was changed into 10 days in the Tang Dynasty (AD 618 – 907), called huan or xún (旬). Months were almost three weeks long (alternating 29 and 30 days to keep in line with the lunation). The weeks were labelled shàng xún (上旬), zhōng xún (中旬), and xià xún (下旬) which mean roughly "upper", "middle" and "lower" week.


Ancient Egypt had a ten-day week, three weeks per month with five extra days at the end of the year.

Revolutionary France

The French Republican Calendar consisted of three ten-day weeks in a month called décades

Other calendar intervals


Restored Aztec sun stone showing the 20 Days

The Aztecs divided a ritual cycle of 260 days, known as Tonalpohualli, into 20 weeks of 13 days known as Trecena.

The Aztecs divided a solar year of 365 days, Xiuhpohualli, into 18 periods of 20 days and five nameless days known as Nemontemi. Although some call this 20-day division or grouping a month, it has no relation to a lunation and therefore the word "week" is more appropriate.[citation needed]


The Maya divided a 260-day ritual cycle known Tzolk'in into 20 weeks of 13 days known as Trecena.

The Maya also divided the year, Haab', into 18 periods of 20 days, Uinal, and five nameless days known as Wayeb'.

Bali, Indonesia

The Pawukon is a 210-day calendar consisting of 10 different concurrent weeks of 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 days.


  1. ^ OED s.v. "week n.", entry 1.c.: "Sometimes applied transf. to other artificial cycles of a few days that have been employed by various peoples"
  2. ^ Senn, Frank C. (1997). Christian Liturgy: Catholic and Evangelical. Fortress Press. ISBN 0800627261, 9780800627263. http://books.google.com/?id=g5c7C2rQzU0C. 
  3. ^ Pinches, T.G. (2003). "Sabbath (Babylonian)". In Hastings, James. Encyclopedia of Religion and Ethics. 20. Selbie, John A., contrib. Kessinger Publishing. pp. 889–891. ISBN 9780766136984. http://books.google.com/books?id=qVNqXDz4CE8C. Retrieved 2009-03-17. 
  4. ^ Zerubavel, Eviatar (1989). The Seven Day Circle: The History and Meaning of the Week. University of Chicago Press. pp. 45. ISBN 0226981657, 9780226981659. http://books.google.com/books?id=Cd5ZjRsNj4sC. 
  5. ^ Dialogue with Trypho, chapter XLI
  6. ^ Meyer, Peter (2005-02-21). "Hermetic Lunar Week Calendar". Hermetic Systems. http://www.hermetic.ch/cal_stud/hlwc/hlwc.htm. Retrieved 2009-01-21. 
  7. ^ Astronomy and Basque Language, Henrike Knörr, Oxford VI and SEAC 99 "Astronomy and Cultural Diversity", La Laguna, June 1999. It references Alessandro Bausani, 1982, The prehistoric Basque week of three days: archaeoastronomical notes, The Bulletin of the Center for Archaeoastronomy (Maryland), v. 2, 16-22.
  8. ^ Bartle, Philip F.W. (1978). "Forty Days: The Akan Calendar". Africa: Journal of the International African Institute (Edinburgh University Press) 48 (1): 80–84. doi:10.2307/1158712. JSTOR 1158712. http://www.scn.org/rdi/kw-40.htm. Retrieved 2009-01-21. 
  9. ^ Apology, chapter LXVII
  10. ^ Zerubavel, Eviatar (1989). The Seven Day Circle: The History and Meaning of the Week. University of Chicago Press. pp. 45. ISBN 0226981657, 9780226981659. http://books.google.com/?id=Cd5ZjRsNj4sC. 
  11. ^ Rhys (1840-1915), Sir John (1892). Lectures on the Origin and Growth of Religion as Illustrated by Celtic Heathendom. pp. 360–382. http://www.archive.org/details/lecturesonorigin00rhys. 
  12. ^ Gusev, M. (1865) (in Russian). The Ancient Lithuanian Calendar. 5. St. Petersburg: Izvestia of the Imperial Archaeological Society. pp. 335. 
  13. ^ Straižys, Vytautas; Klimka, Libertas. "Natural rythms and calendar". Cosmology of the Ancient Balts. Global Lithuanian Net. http://www.lithuanian.net/mitai/cosmos/baltai5.htm. Retrieved 2009-01-21. 
  14. ^ Wilkinson, Endymion Porter. Chinese History: A Manual. Harvard University Asia Center. pp. 176. ISBN 9780674002494. 

Further reading

  • Colson, Francis Henry (1926). The Week: An Essay on the Origin and Development of the Seven-day Cycle. Cambridge University Press. OCLC 59110177. 

External links

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Look at other dictionaries:

  • week — W1S1 [wi:k] n [: Old English; Origin: wicu] 1.) a period of seven days and nights, usually measured in Britain from Monday to Sunday and in the US from Sunday to Saturday once/twice/three times etc a week ▪ Letters were delivered twice a week… …   Dictionary of contemporary English

  • week — [ wik ] noun count *** a period of seven days, usually counted from a Sunday: He travels south two days a week. That left 15 dollars per week for food. last/next week: He will meet his uncle in Boston next week. a. a week in which particular… …   Usage of the words and phrases in modern English

  • week — [wēk] n. [ME weke < OE wicu with lengthened & lowered vowel, akin to Ger woche (OHG wohha) < IE * weig , to bend (see WEAK): basic sense “period of change”] 1. a period of seven days, esp. one beginning with Sunday and ending with Saturday… …   English World dictionary

  • week — /week/, n. 1. a period of seven successive days, usually understood as beginning with Sunday and ending with Saturday. 2. a period of seven successive days that begins with or includes an indicated day: the week of June 3; Christmas week. 3.… …   Universalium

  • week|ly — «WEEK lee», adjective, adverb, noun, plural lies. –adj. 1. of a week; for a week; lasting a week. 2. done, happening, or appearing once a week or each week: »She writes a weekly letter to her grandmother. 3. of or having to do with the working… …   Useful english dictionary

  • Week — Week, n. [OE. weke, wike, woke, wuke AS. weocu, wicu, wucu; akin to OS. wika, OFries. wike, D. week, G. woche, OHG. wohha, wehha, Icel. vika, Sw. vecka, Dan. uge, Goth. wik?, probably originally meaning, a succession or change, and akin to G.… …   The Collaborative International Dictionary of English

  • week — O.E. wice, from P.Gmc. *wikon (Cf. O.N. vika, O.Fris. wike, M.Du. weke, O.H.G. wecha, Ger. woche), probably originally with the sense of a turning or succession (Cf. Goth. wikon in the course of, O.N. vika sea mile, originally change of oar …   Etymology dictionary

  • week in — week in, week out Continuously without a break • • • Main Entry: ↑week …   Useful english dictionary

  • week — ► NOUN 1) a period of seven days. 2) the period of seven days generally reckoned from and to midnight on Saturday night. 3) chiefly Brit. (preceded by a specified day) a week after (that day). 4) the five days from Monday to Friday, or the time… …   English terms dictionary

  • week — n. 1) to spend a week (somewhere) 2) last; next; this week 3) a week from (Tuesday) 4) by the week (she is paid by the week) 5) during the week 6) for a week (they came here for a week) 7) for weeks (she hasn t been here for weeks; AE also has:… …   Combinatory dictionary

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