Week
Encyclopedia
A week is a time unit equal to seven days
Seven-day week
The seven-day week is used by the majority of the world and is the international standard as specified in ISO 8601.- Origins :The origin of the seven-day week is the religious significance that was placed on the seventh day by ancient cultures, including the Babylonian civilization and the Jewish...

.

The English word week continues an Old English wice, ultimately from a Common Germanic , from a root "turn, move, change". The Germanic word probably had a wider meaning prior to the adoption of the Roman calendar
Roman calendar
The Roman calendar changed its form several times in the time between the founding of Rome and the fall of the Roman Empire. This article generally discusses the early Roman or pre-Julian calendars...

, perhaps "succession series", as suggested by Gothic
Gothic language
Gothic is an extinct Germanic language that was spoken by the Goths. It is known primarily from the Codex Argenteus, a 6th-century copy of a 4th-century Bible translation, and is the only East Germanic language with a sizable Text corpus...

 wikō translating taxis "order" in Luke
Gospel of Luke
The Gospel According to Luke , commonly shortened to the Gospel of Luke or simply Luke, is the third and longest of the four canonical Gospels. This synoptic gospel is an account of the life and ministry of Jesus of Nazareth. It details his story from the events of his birth to his Ascension.The...

 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.
Intervals longer than 10 days are not usually termed "weeks" as they are closer in length to the fortnight
Fortnight
The fortnight is a unit of time equal to fourteen days, or two weeks. The word derives from the Old English fēowertyne niht, meaning "fourteen nights"....

 or the month
Month
A month is a unit of time, used with calendars, which was first used and invented in Mesopotamia, as a natural period related to the motion of the Moon; month and Moon are cognates. The traditional concept arose with the cycle of moon phases; such months are synodic months and last approximately...

 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
Babylonian captivity
The Babylonian captivity was the period in Jewish history during which the Jews of the ancient Kingdom of Judah were captives in Babylon—conventionally 587–538 BCE....

 of the 6th century BC. Both Judaism (based on the Creation narrative in the Torah/Bible) and ancient Babylonian religions used a seven-day week. Other cultures adopted the seven-day week at different times. Between the 1st and 3rd centuries the Roman Empire
Roman Empire
The Roman Empire was the post-Republican period of the ancient Roman civilization, characterised by an autocratic form of government and large territorial holdings in Europe and around the Mediterranean....

 gradually replaced the eight-day Roman nundinal cycle with the seven-day week. The seven day week begins on a Sunday. Hindus may have adopted a seven day week earlier than 11th century BC. See Rig Veda. There is evidence of some Chinese groups using a seven day week as early as 4th century AD.

Soviet Union


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.

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
Gregorian calendar
The Gregorian calendar, also known as the Western calendar, or Christian calendar, is the internationally accepted civil calendar. It was introduced by Pope Gregory XIII, after whom the calendar was named, by a decree signed on 24 February 1582, a papal bull known by its opening words Inter...

 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
February
February is the second month of the year in the Julian and Gregorian calendars. It is the shortest month and the only month with fewer than 30 days. The month has 28 days in common years and 29 days in leap years...

 is only 28 or 29 days depending on whether it is a leap year
Leap year
A leap year is a year containing one extra day in order to keep the calendar year synchronized with the astronomical or seasonal 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.

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

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
Justin Martyr
Justin Martyr, also known as just Saint Justin , was an early Christian apologist. Most of his works are lost, but two apologies and a dialogue survive. He is considered a saint by the Roman Catholic Church and the Eastern Orthodox Church....

 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". 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
Octave (liturgical)
"Octave" has two senses in Christian liturgical usage. In the first sense, it is the eighth day after a feast, reckoning inclusively, and so always falls on the same day of the week as the feast itself. The word is derived from Latin octava , with dies understood...

. 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
Pentecost
Pentecost is a prominent feast in the calendar of Ancient Israel celebrating the giving of the Law on Sinai, and also later in the Christian liturgical year commemorating the descent of the Holy Spirit upon the disciples of Christ after the Resurrection of Jesus...

. Organizations such as 8th Day Center for Justice
8th Day Center for Justice
8th Day Center for Justice is a Roman Catholic non-profit organization based in Chicago, Illinois. Named after the Christian concept of an "eighth day", it was founded in 1974 by six congregations of religious men and women...

, 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
Lunation
Lunation is the mean time for one lunar phase cycle .  It is on average 29.530589 days, or 29 days 12 hours 44 minutes and 3 seconds...

 is divided into the four moon phases
Lunar phase
A lunar phase or phase of the moon is the appearance of the illuminated portion of the Moon as seen by an observer, usually on Earth. The lunar phases change cyclically as the Moon orbits the Earth, according to the changing relative positions of the Earth, Moon, and Sun...

 and has six, seven, eight, or nine days depending on the actual time difference between the full moon
Full moon
Full moon lunar phase that occurs when the Moon is on the opposite side of the Earth from the Sun. More precisely, a full moon occurs when the geocentric apparent longitudes of the Sun and Moon differ by 180 degrees; the Moon is then in opposition with the Sun.Lunar eclipses can only occur at...

, first quarter, new moon
New moon
In astronomical terminology, the new moon is the lunar phase that occurs when the Moon, in its monthly orbital motion around Earth, lies between Earth and the Sun, and is therefore in conjunction with the Sun as seen from Earth...

 and last quarter.

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

Four-day

The Igbo
Igbo people
Igbo people, also referred to as the Ibo, Ebo, Eboans or Heebo are an ethnic group living chiefly in southeastern Nigeria. They speak Igbo, which includes various Igboid languages and dialects; today, a majority of them speak English alongside Igbo as a result of British colonialism...

 of Nigeria
Nigeria
Nigeria , officially the Federal Republic of Nigeria, is a federal constitutional republic comprising 36 states and its Federal Capital Territory, Abuja. The country is located in West Africa and shares land borders with the Republic of Benin in the west, Chad and Cameroon in the east, and Niger in...

 have a traditional calendar with a four-day week. This "market week" features prominently in the fiction of Chinua Achebe
Chinua Achebe
Albert Chinụalụmọgụ Achebe popularly known as Chinua Achebe is a Nigerian novelist, poet, professor, and critic...

.

Five-day

The Javanese people of Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...

 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
Islamic calendar
The Hijri calendar , also known as the Muslim calendar or Islamic calendar , is a lunar calendar consisting of 12 lunar months in a year of 354 or 355 days. It is used to date events in many Muslim countries , and used by Muslims everywhere to determine the proper day on which to celebrate Islamic...

 to become what is known as the 35-day Wetonan Cycle.

Six-day

The Akan people
Akan people
The Akan people are an ethnic group found predominately in Ghana and The Ivory Coast. Akans are the majority in both of these countries and overall have a population of over 20 million people.The Akan speak Kwa languages-Origin and ethnogenesis:...

 of West Africa
West Africa
West Africa or Western Africa is the westernmost region of the African continent. Geopolitically, the UN definition of Western Africa includes the following 16 countries and an area of approximately 5 million square km:-Flags 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 extant 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. The six-day week is referred to as Nanson (literally seven-days), reflecting an inclusive numbering system.

Nundinal cycle

The ancient Etruscans developed an eight-day market week known as the nundinal cycle around the 8th or 7th century BC
Anno Domini
and Before Christ are designations used to label or number years used with the Julian and Gregorian calendars....

. This was passed on to the Romans
Ancient Rome
Ancient Rome was a thriving civilization that grew on the Italian Peninsula as early as the 8th century BC. Located along the Mediterranean Sea and centered on the city of Rome, it expanded to one of the largest empires in the ancient world....

 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
Justin Martyr
Justin Martyr, also known as just Saint Justin , was an early Christian apologist. Most of his works are lost, but two apologies and a dialogue survive. He is considered a saint by the Roman Catholic Church and the Eastern Orthodox Church....

, who wrote of the Christians meeting on the Day of the Sun (Sunday).

Emperor Constantine eventually established the seven-day week in the Roman calendar
Roman calendar
The Roman calendar changed its form several times in the time between the founding of Rome and the fall of the Roman Empire. This article generally discusses the early Roman or pre-Julian calendars...

 in AD 321.

Celts

It is believed the ancient Celts of the British Isles
British Isles
The British Isles are a group of islands off the northwest coast of continental Europe that include the islands of Great Britain and Ireland and over six thousand smaller isles. There are two sovereign states located on the islands: the United Kingdom of Great Britain and Northern Ireland and...

 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.

Marathi

The Marathi language describes a week as Athavada which means group of eight days and nine nights, though nowadays a seven day week is accepted and used according the roman calender.In Marathi calendars the lunar tithis (lunar dates) are printed alongside the date and day of the seven day week used nowadays.The days are: Sunday means Ravivar named after the sun, Monday means somwar named after the moon, Tuesday is mangalwar named after planet Mars, Wednesday is budhwar named after the planet Mercury, Thursday is Guruvar named after the planet Jupiter, Friday is Shukrawar named after the planet Venus, Saturday is Shanivar named after the planet Saturn and back to Sunday (ravivar).

Nine-day

Baltic calendars

In the 14th century, the Grand Duchy of Lithuania
Grand Duchy of Lithuania
The Grand Duchy of Lithuania was a European state from the 12th /13th century until 1569 and then as a constituent part of Polish-Lithuanian Commonwealth until 1791 when Constitution of May 3, 1791 abolished it in favor of unitary state. It was founded by the Lithuanians, one of the polytheistic...

 used a solar-lunar calendar. The structure of this calendar was understood with the help of the so-called Gediminas Sceptre discovered in 1680.

Historical records give evidence that the week of the ancient Balts
Balts
The Balts or Baltic peoples , defined as speakers of one of the Baltic languages, a branch of the Indo-European language family, are descended from a group of Indo-European tribes who settled the area between the Jutland peninsula in the west and Moscow, Oka and Volga rivers basins in the east...

 was nine days long. Thus, the sidereal month must have been divided into three parts.

China

The Chinese ten-day week went as far back as the Shang Dynasty
Shang Dynasty
The Shang Dynasty or Yin Dynasty was, according to traditional sources, the second Chinese dynasty, after the Xia. They ruled in the northeastern regions of the area known as "China proper" in the Yellow River valley...

 (1200-1045 BC). The law in the Han Dynasty
Han Dynasty
The Han Dynasty was the second imperial dynasty of China, preceded by the Qin Dynasty and succeeded by the Three Kingdoms . It was founded by the rebel leader Liu Bang, known posthumously as Emperor Gaozu of Han. It was briefly interrupted by the Xin Dynasty of the former regent Wang Mang...

 (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
Tang Dynasty
The Tang Dynasty was an imperial dynasty of China preceded by the Sui Dynasty and followed by the Five Dynasties and Ten Kingdoms Period. It was founded by the Li family, who seized power during the decline and collapse of the Sui Empire...

 (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
Lunation
Lunation is the mean time for one lunar phase cycle .  It is on average 29.530589 days, or 29 days 12 hours 44 minutes and 3 seconds...

). 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.

Egypt

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
French Republican Calendar
The French Republican Calendar or French Revolutionary Calendar was a calendar created and implemented during the French Revolution, and used by the French government for about 12 years from late 1793 to 1805, and for 18 days by the Paris Commune in 1871...

 consisted of three ten-day weeks in a month called décades

Aztecs


The Aztecs divided a ritual cycle of 260 days, known as Tonalpohualli
Tonalpohualli
The tonalpohualli, a Nahuatl word meaning "count of days", is a 260-day sacred period in use in pre-Columbian Mesoamerica, especially among the Aztecs. This calendrical period is neither solar nor lunar, but rather consists of 20 trecena, or 13-day periods...

, into 20 weeks of 13 days known as Trecena
Trecena
A trecena is a 13-day period used in pre-Columbian Mesoamerican calendars. The 260-day calendar was divided into 20 trecenas. Trecena is derived from the Spanish chroniclers and translates to 'a group of thirteen' in the same way that a dozen relates to the number twelve...

.

The Aztecs divided a solar year of 365 days, Xiuhpohualli
Xiuhpohualli
The Xiuhpohualli was a 365-day calendar used by the Aztecs and other pre-Columbian Nahua peoples in central Mexico. It was composed of eighteen 20-day "months," called veintenas or metzli with a separate 5 day period at the end of the year called the nemontemi...

, 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
Lunation
Lunation is the mean time for one lunar phase cycle .  It is on average 29.530589 days, or 29 days 12 hours 44 minutes and 3 seconds...

 and therefore the word "week" is more appropriate.

Maya

The Maya divided a 260-day ritual cycle known Tzolk'in
Tzolk'in
Tzolk'in is the name bestowed by Mayanists on the 260-day Mesoamerican calendar used by the Maya civilization of pre-Columbian Mesoamerica.The tzolk'in, the basic cycle of the Maya calendar, is a pre-eminent...

 into 20 weeks of 13 days known as Trecena
Trecena
A trecena is a 13-day period used in pre-Columbian Mesoamerican calendars. The 260-day calendar was divided into 20 trecenas. Trecena is derived from the Spanish chroniclers and translates to 'a group of thirteen' in the same way that a dozen relates to the number twelve...

.

The Maya also divided the year, Haab'
Haab'
The Haab is part of the Maya calendric system. It was the Maya version of the 365-day calendar known to many of the pre-Columbian cultures of Mesoamerica...

, 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.

External links

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