Definition of the word week

A week is a unit of time equal to seven days. It is the standard time period used for short cycles of days in most parts of the world. The days are often used to indicate common work days and rest days, as well as days of worship. Weeks are often mapped against yearly calendars, but are typically not the basis for them, as weeks are not based on astronomy.

The modern seven-day week can be traced back to the Babylonians, who used it within their calendar. Other ancient cultures had different week lengths, including ten in Egypt and an eight-day week for Etruscans. The Etruscan week was adopted by the Ancient Romans, but they later moved to a seven-day week, which had spread across Western Asia and the Eastern Mediterranean. In 321 CE, Emperor Constantine officially decreed a seven-day week in the Roman Empire, including making Sunday a public holiday.^[1][2] This later spread across Europe, then the rest of the world.

In English, the names of the days of the week are Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, and Sunday. In many languages, the days of the week are named after gods or planets visible to the eye. Such a week may be called a planetary week.^[4] Certain weeks within a year may be designated for a particular purpose, such as Holy Week in Christianity, Golden Week in China, and National Family Week in Canada. More informally, certain groups may advocate awareness weeks, which are designed to draw attention to a certain subject or cause. The term «week» may also be used to refer to a sub-section of the week, such as the workweek and weekend.

Cultures vary in which days of the week are designated the first and the last, though virtually all have Saturday, Sunday or Monday as the first day. The Geneva-based ISO standards organization uses Monday as the first day of the week in its ISO week date system through the international ISO 8601 standard.^[a] Most of Europe and China consider Monday the first day of the week, most of North America and South Asia consider Sunday the first day, while Saturday is judged as the first day of the week in much of the Middle East and North Africa. Other regions are mixed, but typically observe either Sunday or Monday as the first day.^[3] The Jewish week ends with nightfall on Saturday, at the conclusion of the Sabbath, following the Hebrew Bible in which God created the world in six days and rested on the seventh. Christians set their Sabbath to Sunday, so as not to coincide with Judaism. Muslims set their Sabbath to Friday because it was described as a sacred day of worship in the Quran.^[5]

Name[edit]

The English word week comes from the 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 seven-day week is named in many languages by a word derived from «seven». The archaism sennight («seven-night») preserves the old Germanic practice of reckoning time by nights, as in the more common fortnight («fourteen-night»).^[6] Hebdomad and hebdomadal week both derive from the Greek hebdomás (ἑβδομάς, «a seven»). Septimana is cognate with the Romance terms derived from Latin septimana («seven mornings»).

Slavic has a formation *tъ(žь)dьnь (Serbian тједан, tjedan, Croatian tjedan, Ukrainian тиждень, tyzhden, Czech týden, Polish tydzień), from *tъ «this» + *dьnь «day». Chinese has 星期, as it were «planetary time unit».

Definition and duration[edit]

A week is defined as an interval of exactly seven days,^[b] so that, except when passing through daylight saving time transitions or leap seconds,

1 week = 7 days = 168 hours = 10,080 minutes = 604,800 seconds.

With respect to the Gregorian calendar:

• 1 Gregorian calendar year = 52 weeks + 1 day (2 days in a leap year)
• 1 week = 1600⁄6957 ≈ 22.9984% of an average Gregorian month

In a Gregorian mean year, there are 365.2425 days, and thus exactly 52+71⁄400 or 52.1775 weeks (unlike the Julian year of 365.25 days or 52+5⁄28 ≈ 52.1786 weeks, which cannot be represented by a finite decimal expansion). There are exactly 20,871 weeks in 400 Gregorian years, so 9 April 1623 was a Sunday just as was 9 April 2023.

Relative to the path of the Moon, a week is 23.659% of an average lunation or 94.637% of an average quarter lunation.

Historically, the system of dominical letters (letters A to G identifying the weekday of the first day of a given year) has been used to facilitate calculation of the day of week.
The day of the week can be easily calculated given a date’s Julian day number (JD, i.e. the integer value at noon UT):
Adding one to the remainder after dividing the Julian day number by seven (JD modulo 7 + 1) yields that date’s ISO 8601 day of the week. For example, the Julian day number of 9 April 2023 is 2460044. Calculating 2460044 mod 7 + 1 yields 7, corresponding to Sunday.^[7] In 1973, John Conway devised the Doomsday rule for mental calculation of the weekday of any date in any year.

Days of the week[edit]

The days of the week were named for the classical planets. This naming system persisted alongside an «ecclesiastical» tradition of numbering the days in ecclesiastical Latin beginning with Dominica (the Lord’s Day) as the first day. The Greco-Roman gods associated with the classical planets were rendered in their interpretatio germanica at some point during the late Roman Empire, yielding the Germanic tradition of names based on indigenous deities.

The ordering of the weekday names is not the classical order of the planets (by distance in the planetary spheres model, nor, equivalently, by their apparent speed of movement in the night sky). Instead, the planetary hours systems resulted in succeeding days being named for planets that are three places apart in their traditional listing. This characteristic was apparently discussed in Plutarch in a treatise written in c. 100 CE, which is reported to have addressed the question of Why are the days named after the planets reckoned in a different order from the actual order? (the text of Plutarch’s treatise has been lost).^[8]

	Sunday	Monday	Tuesday	Wednesday	Thursday	Friday	Saturday
Planet	Sun	Moon	Mars	Mercury	Jupiter	Venus	Saturn
Greco-Roman deity	Helios-Sol	Selene-Luna	Ares-Mars	Hermes-Mercury	Zeus-Jupiter	Aphrodite-Venus	Cronus-Saturn
Greek:[dubious – discuss]	ἡμέρα Ἡλίου[dubious – discuss]	ἡμέρα Σελήνης	ἡμέρα Ἄρεως	ἡμέρα Ἑρμοῦ	ἡμέρα Διός	ἡμέρα Ἀφροδίτης	ἡμέρα Κρόνου
Latin:	dies Sōlis	dies Lūnae	dies Martis	dies Mercuriī	dies Iovis	dies Veneris	dies Saturnī
interpretatio germanica	Sun	Moon	Tiwaz	Wodanaz	Þunraz	Frige	—
Old English	sunnandæg	mōnandæg	tiwesdæg	wōdnesdæg	þunresdæg	frīgedæg	sæterndæg
Vedic Navagraha	Suryavara/ Raviwara/ Bhanuvasarey	Chandravara/ Somawara/ Induvasarey	Mangalavara/ Bhaumavasarey	Budhavara/ Sowmyavasarey	Bṛhaspativara/ Guruwara/ Bṛhaspativasarey	Shukravara/ Bṛhguvasarey	Shanivara/ Sthiravasarey

An ecclesiastical, non-astrological, system of numbering the days of the week was adopted in Late Antiquity. This model also seems to have influenced (presumably via Gothic) the designation of Wednesday as «mid-week» in Old High German (mittawehha) and Old Church Slavonic (срѣда). Old Church Slavonic may have also modeled the name of Monday, понєдѣльникъ, after the Latin feria Secunda.^[9] The ecclesiastical system became prevalent in Eastern Christianity, but in the Latin West it remains extant only in modern Icelandic, Galician, and Portuguese.^[10]

	«First Day» or «Lord’s Day» (Sunday)	«Second Day» (Monday)	«Third Day» (Tuesday)	«Fourth Day» (Wednesday)	«Fifth Day» (Thursday)	«Sixth Day» (Friday)	«Seventh Day» or «Sabbath» (Saturday)
Greek	Κυριακὴ ἡμέρα /kiriaki iméra/	Δευτέρα ἡμέρα /devtéra iméra/	Τρίτη ἡμέρα /tríti iméra/	Τετάρτη ἡμέρα /tetárti iméra/	Πέμπτη ἡμέρα /pémpti iméra/	Παρασκευὴ ἡμέρα /paraskevi iméra/[11]	Σάββατον /sáb:aton/
Latin	[dies] dominica; rarely feria prima, feria dominica	feria secunda	feria tertia	feria quarta; rarely media septimana	feria quinta	feria sexta	Sabbatum; dies sabbatinus, dies Sabbati; rarely feria septima, feria Sabbati
Hebrew	Hebrew: יום ראשון, romanized: Yom rishon, lit. ‘first day’	Hebrew: יום שני, romanized: Yom sheni, lit. ‘second day’	Hebrew: יום שלישי, romanized: Yom shlishi, lit. ‘third day’	Hebrew: יום רביעי, romanized: Yom revi’i, lit. ‘fourth day’	Hebrew: יום חמישי, romanized: Yom chamishi, lit. ‘fifth day’	Hebrew: יום שישי, romanized: Yom shishi, lit. ‘sixth day’	Hebrew: שבת, romanized: Shabbat, lit. ‘Rest/cessation’

History[edit]

Ancient Near East[edit]

The earliest evidence of an astrological significance of a seven-day period is connected to Gudea, the priest-king of Lagash in Sumer during the Gutian dynasty (about 2100 BCE), who built a seven-room temple, which he dedicated with a seven-day festival. In the flood story of the Assyro-Babylonian Epic of Gilgamesh, the storm lasts for seven days, the dove is sent out after seven days, and the Noah-like character of Utnapishtim leaves the ark seven days after it reaches the firm ground. ^[c]

Counting from the new moon, the Babylonians celebrated the 7th, 14th, 21st and 28th as «holy days», also called «evil days» (meaning inauspicious for certain activities). On these days, officials were prohibited from various activities and common men were forbidden to «make a wish», and at least the 28th was known as a «rest day».^[15]
On each of them, offerings were made to a different god and goddess.

Judaism[edit]

A continuous seven-day cycle that runs throughout history without reference to the phases of the moon was first practiced in Judaism, dated to the 6th century BCE at the latest.^[16][17]

There are several hypotheses concerning the origin of the biblical seven-day cycle.

Friedrich Delitzsch and others suggested that the seven-day week being approximately a quarter of a lunation is the implicit astronomical origin of the seven-day week,^[18] and indeed the Babylonian calendar used intercalary days to synchronize the last week of a month with the new moon.^[19] According to this theory, the Jewish week was adopted from the Babylonians while removing the moon-dependency.

George Aaron Barton speculated that the seven-day creation account of Genesis is connected to the Babylonian creation epic, Enûma Eliš, which is recorded on seven tablets.^[20]

In a frequently-quoted suggestion going back to the early 20th century,^[21] the Hebrew Sabbath is compared to the Sumerian sa-bat «mid-rest», a term for the full moon. The Sumerian term has been reconstructed as rendered Sapattu^m or Sabattu^m in Babylonian, possibly present in the lost fifth tablet of the Enûma Eliš, tentatively reconstructed^{[according to whom?]} «[Sa]bbath shalt thou then encounter, mid[month]ly».^[15]

However, Niels-Erik Andreasen, Jeffrey H. Tigay, and others claim that the Biblical Sabbath is mentioned as a day of rest in some of the earliest layers of the Pentateuch dated to the 9th century BCE at the latest, centuries before the Babylonian exile of Judah. They also find the resemblance between the Biblical Sabbath and the Babylonian system to be weak. Therefore, they suggest that the seven-day week may reflect an independent Israelite tradition.^{[22][23][24][25]} Tigay writes:

It is clear that among neighboring nations that were in position to have an influence over Israel – and in fact which did influence it in various matters – there is no precise parallel to the Israelite Sabbatical week. This leads to the conclusion that the Sabbatical week, which is as unique to Israel as the Sabbath from which it flows, is an independent Israelite creation.^[24][26]

The seven-day week seems to have been adopted, at different stages, by the Persian Empire, in Hellenistic astrology, and (via Greek transmission) in Gupta India and Tang China. ^{[d][citation needed]}
The Babylonian system was received by the Greeks in the 4th century BCE (notably via Eudoxus of Cnidus). However, the designation of the seven days of the week to the seven planets is an innovation introduced in the time of Augustus.^[28] The astrological concept of planetary hours is rather an original innovation of Hellenistic astrology, probably first conceived in the 2nd century BCE.^[29]

The seven-day week was widely known throughout the Roman Empire by the 1st century CE,^[28] along with references to the Jewish Sabbath by Roman authors such as Seneca and Ovid.^[30] When the seven-day week came into use in Rome during the early imperial period, it did not immediately replace the older eight-day nundinal system.^[31] The nundinal system had probably fallen out of use by the time Emperor Constantine adopted the seven-day week for official use in CE 321, making the Day of the Sun (dies Solis) a legal holiday.^[32]

Achaemenid period[edit]

The Zoroastrian calendar follows the Babylonian in relating the 7th, 14th, 21st, and 28th of the month to Ahura Mazda.^[33]
The forerunner of all modern Zoroastrian calendars is the system used to determine dates in the Persian Empire, adopted from the Babylonian calendar by the 4th century BCE.

Frank C. Senn in his book Christian Liturgy: Catholic and Evangelical points to data suggesting evidence of an early continuous use of a seven-day week; referring to the Jews during the Babylonian captivity in the 6th century BCE,^[17] after the destruction of the Temple of Solomon.
While the seven-day week in Judaism is tied to Creation account in the Book of Genesis in the Hebrew Bible (where God creates the heavens and the earth in six days and rests on the seventh; Genesis 1:1-2:3,^[34] in the Book of Exodus, the fourth of the Ten Commandments is to rest on the seventh day, Shabbat, which can be seen as implying a socially instituted seven-day week), it is not clear whether the Genesis narrative predates the Babylonian captivity of the Jews in the 6th century BCE. At least since the Second Temple period under Persian rule, Judaism relied on the seven-day cycle of recurring Sabbaths.^[17]

Tablets^{[citation needed]} from the Achaemenid period indicate that the lunation of 29 or 30 days basically contained three seven-day weeks, and a final week of eight or nine days inclusive, breaking the continuous seven-day cycle.^[15]
The Babylonians additionally celebrated the 19th as a special «evil day», the «day of anger», because it was roughly the 49th day of the (preceding) month, completing a «week of weeks», also with sacrifices and prohibitions.^[15]

Difficulties with Friedrich Delitzsch’s origin theory connecting Hebrew Shabbat with the Babylonian lunar cycle^[35] include reconciling the differences between an unbroken week and a lunar week, and explaining the absence of texts naming the lunar week as Shabbat in any language.^[36]

Hellenistic and Roman era[edit]

In Jewish sources by the time of the Septuagint, the term «Sabbath» (Greek Sabbaton) by synecdoche also came to refer to an entire seven-day week,^[37] the interval between two weekly Sabbaths.
Jesus’s parable of the Pharisee and the Publican (Luke 18:12) describes the Pharisee as fasting «twice in the week» (Greek δὶς τοῦ σαββάτου dis tou sabbatou).
Days of the week are called «days of the sabbath» in the Hebrew language. In the account of the women finding the tomb empty, they are described as coming there Greek: εις μια των σαββατων, lit. ‘toward the first [day] of the sabbath’,^[38] though modern translations often substitute «week» for «sabbath».

The ancient Romans traditionally used the eight-day nundinum but, after the Julian calendar had come into effect in 45 BCE, the seven-day week came into increasing use. For a while, the week and the nundinal cycle coexisted, but by the time the week was officially adopted by Constantine in 321 CE, the nundinal cycle had fallen out of use. The association of the days of the week with the Sun, the Moon and the five planets visible to the naked eye dates to the Roman era (2nd century).^[39][17]

The continuous seven-day cycle of the days of the week can be traced back to the reign of Augustus; the first identifiable date cited complete with day of the week is 6 February 60 CE, identified as a «Sunday» (as viii idus Februarius dies solis «eighth day before the ides of February, day of the Sun») in a Pompeiian graffito. According to the (contemporary) Julian calendar, 6 February 60 was, however, a Wednesday. This is explained by the existence of two conventions of naming days of the weeks based on the planetary hours system: 6 February was a «Sunday» based on the sunset naming convention, and a «Wednesday» based on the sunrise naming convention.^[40]

Islamic concept[edit]

According to Islamic beliefs, the seven-day a week concept started with the creation of the universe by Allah. Abu Huraira reported that Muhammad said: Allah, the Exalted and Glorious, created the clay on Saturday and He created the mountains on Sunday and He created the trees on Monday and He created the things entailing labour on Tuesday and created light on Wednesday and He caused the animals to spread on Thursday and created Adam after ‘Asr on Friday; the last creation at the last hour of the hours of Friday, i. e. between afternoon and night.^[41]

Adoption in Asia[edit]

China and Japan[edit]

The earliest known reference in Chinese writings to a seven-day week is attributed to Fan Ning, who lived in the late 4th century in the Jin dynasty, while diffusions from the Manichaeans are documented with the writings of the Chinese Buddhist monk Yi Jing and the Ceylonese or Central Asian Buddhist monk Bu Kong of the 7th century (Tang dynasty).

The Chinese variant of the planetary system was brought to Japan by the Japanese monk Kūkai (9th century). Surviving diaries of the Japanese statesman Fujiwara Michinaga show the seven-day system in use in Heian Period Japan as early as 1007. In Japan, the seven-day system was kept in use for astrological purposes until its promotion to a full-fledged Western-style calendrical basis during the Meiji Period (1868–1912).

India[edit]

The seven-day week was known in India by the 6th century, referenced in the Pañcasiddhāntikā.^{[citation needed]} Shashi (2000) mentions the Garga Samhita, which he places in the 1st century BCE or CE, as a possible earlier reference to a seven-day week in India. He concludes «the above references furnish a terminus ad quem (viz. 1st century) The terminus a quo cannot be stated with certainty».^[42][43]

Christian Europe[edit]

The seven-day weekly cycle has remained unbroken in Christendom, and hence in Western history, for almost two millennia, despite changes to the Coptic, Julian, and Gregorian calendars, demonstrated by the date of Easter Sunday having been traced back through numerous computistic tables to an Ethiopic copy of an early Alexandrian table beginning with the Easter of 311 CE.^[44][45]

A tradition of divinations arranged for the days of the week on which certain feast days occur develops in the Early Medieval period. There are many later variants of this, including the German Bauern-Praktik and the versions of Erra Pater published in 16th to 17th century England, mocked in Samuel Butler’s Hudibras. South and East Slavic versions are known as koliadniki (from koliada, a loan of Latin calendae), with Bulgarian copies dating from the 13th century, and Serbian versions from the 14th century.^[46]

Medieval Christian traditions associated with the lucky or unlucky nature of certain days of the week survived into the modern period. This concerns primarily Friday, associated with the crucifixion of Jesus. Sunday, sometimes personified as Saint Anastasia, was itself an object of worship in Russia, a practice denounced in a sermon extant in copies going back to the 14th century.^[47]

Sunday, in the ecclesiastical numbering system also counted as the feria prima or the first day of the week; yet, at the same time, figures as the «eighth day», and has occasionally been so called in Christian liturgy.
^[e]

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.»^[48]

A period of eight days, usually (but not always, mainly because of Christmas Day) starting and ending on a Sunday, is called an octave, particularly in Roman Catholic liturgy. In German, the phrase heute in acht Tagen (literally «today in eight days») can also mean one week from today (i.e. on the same weekday). The same is true of the Italian phrase oggi otto (literally «today eight») and the French à huitaine.

Numbering[edit]

Weeks in a Gregorian calendar year can be numbered for each year. This style of numbering is often used in European and Asian countries. It is less common in the U.S. and elsewhere.

The ISO week date system[edit]

The system for numbering weeks is the ISO week date system, which is included in ISO 8601. This system dictates that each week begins on a Monday and is associated with the year that contains that week’s Thursday.

Determining Week 1[edit]

In practice week 1 (W01 in ISO notation) of any year can be determined as follows:

• If January 1 falls on a Monday, Tuesday, Wednesday or Thursday, then the week of January 1 is Week 1. Except in the case of January 1 falling on a Monday, this Week 1 includes the last day(s) of the previous year.
• If January 1 falls on a Friday, Saturday, or Sunday, then January 1 is considered to be part of the last week of the previous year. Week 1 will begin on the first Monday after January 1.

Examples:

• Week 1 of 2015 (2015W01 in ISO notation) started on Monday, 29 December 2014 and ended on Sunday, 4 January 2015, because 1 January 2015 fell on Thursday.
• Week 1 of 2021 (2021W01 in ISO notation) started on Monday, 4 January 2021 and ended on Sunday, 10 January 2021, because 1 January 2021 fell on Friday.

Week 52 and 53[edit]

It is also possible to determine if the last week of the previous year was Week 52 or Week 53 as follows:

• If January 1 falls on a Friday, then it is part of Week 53 of the previous year (W53-5).
• If January 1 falls on a Saturday,
  • then it is part of Week 53 of the previous year if that is a leap year (W53-6),
  • and part of Week 52 otherwise (W52-6), i.e. if the previous year is a common year.
• If January 1 falls on a Sunday, then it is part of Week 52 of the previous year (W52-7).

Schematic representation of ISO week date[edit]

Dominical letter(s) plus weekdays, dates and week numbers at the beginning and end of a year

Dominical letter(s)1	Days at the start of January	Effect1,2	Days at the end of December1
1 Mon	2 Tue	3 Wed	4 Thu	5 Fri	6 Sat	7 Sun	W01-13	01 Jan week	…	31 Dec week	1 Mon4	2 Tue	3 Wed	4 Thu	5 Fri	6 Sat	7 Sun
G(F)	01	02	03	04	05	06	07	01 Jan	W01	…	W01	31 (30)	(31)
F(E)		01	02	03	04	05	06	31 Dec	W01	…	W01	30 (29)	31 (30)	(31)
E(D)			01	02	03	04	05	30 Dec	W01	…	W01 (W53)	29 (28)	30 (29)	31 (30)	(31)
D(C)				01	02	03	04	29 Dec	W01	…	W53	28 (27)	29 (28)	30 (29)	31 (30)	(31)
C(B)					01	02	03	04 Jan	W53	…	W52	27 (26)	28 (27)	29 (28)	30 (29)	31 (30)	(31)
B(A)						01	02	03 Jan	W52 (W53)	…	W52	26 (25)	27 (26)	28 (27)	29 (28)	30 (29)	31 (30)	(31)
A(G)							01	02 Jan	W52	…	W52 (W01)	25 (31)	26 (25)	27 (26)	28 (27)	29 (28)	30 (29)	31 (30)

Notes
1. Numbers and letters in parentheses, ( ), apply to March − December in leap years.
2. Underlined numbers and letters belong to previous year or next year.
3. First date of the first week in the year.
4. First date of the last week in the year.

Other week numbering systems[edit]

In some countries, though, the numbering system is different from the ISO standard. At least six numberings are in use:^{[49][50][dubious – discuss]}

System	First day of week	First week of year contains	Can be last week of previous year	Used by or in
ISO 8601	Monday	4 January	1st Thursday	4–7 days of year	yes	EU (exc. Portugal) and most of other European countries, most of Asia and Oceania
Middle Eastern	Saturday	1 January	1st Friday	1–7 days of year	yes	Much of the Middle East
Western traditional	Sunday	1 January	1st Saturday	1–7 days of year	yes	Canada, United States, Iceland, Portugal, Japan, Taiwan, Thailand, Hong Kong, Macau, Israel, Egypt, South Africa, the Philippines, and most of Latin America
Broadcast Calendar	Monday	1 January	1st Sunday	1–7 days of year	yes	Broadcast services in the United States[51]

Because the week starts on either Saturday, Sunday, or Monday in all these systems, the days in a workweek, Monday through Friday, will always have the same week number within a calendar week system. Quite often, these systems will agree on the week number for each day in a workweek:

• In years where 1 January is a Monday, Tuesday, Wednesday, or Thursday, all of the above week numbering systems will agree.
• In years where 1 January is a Friday, ISO-8601 will be different, but the rest will agree.
• In years where 1 January is a Saturday, ISO-8601 and the Middle Eastern system will agree, being different from Western Traditional and the Broadcast Calendar which will agree.
• In years where 1 January is a Sunday, the Broadcast Calendar will be different, but the rest will agree.

Note that this agreement occurs only for the week number of each day in a work week, not for the day number within the week, nor the week number of the weekends.

The epi week (epidemiological week) is used to report healthcare statistics, as with COVID-19 cases:^[52]

The epidemiological week begins on Sunday and ends on Saturday. The first epidemiological week of the year ends on the first Saturday of January, provided that it falls at least four or more days into the month. Therefore, the first epidemiological week may actually begin in December of the previous year.

Uses[edit]

The semiconductor package date code is often a 4 digit date code YYWW where the first two digits YY are the last 2 digits of the calendar year and the last two digits WW are the two-digit week number.^[53][54]

The tire date code mandated by the US DOT is a 4 digit date code WWYY with two digits of the week number WW followed by the last two digits of the calendar year YY.^[55]

«Weeks» in other calendars[edit]

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.^[56] 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.

Pre-modern calendars[edit]

Calendars unrelated to the Chaldean, Hellenistic, Christian, or Jewish traditions often have time cycles between the day and the month of varying lengths, sometimes also called «weeks».

An eight-day week was used in Ancient Rome and possibly in the pre-Christian Celtic calendar. Traces of a nine-day week are found in Baltic languages and in Welsh. The ancient Chinese calendar had a ten-day week, as did the ancient Egyptian calendar (and, incidentally, the French Republican Calendar, dividing its 30-day months into thirds).

A six-day week is found in the Akan Calendar and Kabiye culture until 1981. Several cultures used a five-day week, including the 10th century Icelandic calendar, the Javanese calendar, and the traditional cycle of market days in Korea.^{[citation needed]} The Igbo have a «market week» of four days. Evidence of a «three-day week» has been derived from the names of the days of the week in Guipuscoan Basque.^[57]

The Aztecs and Mayas used the Mesoamerican calendars. The most important of these calendars divided a ritual cycle of 260 days (known as Tonalpohualli in Nahuatl and Tzolk’in in Yucatec Maya) into 20 weeks of 13 days (known in Spanish as trecenas). They also divided the solar year into 18 periods (winal) of 20 days and five nameless days (wayebʼ), creating a 20-day month divided into four five-day weeks. The end of each five-day week was a market day.^[58][59]

The Balinese Pawukon is a 210-day calendar consisting of 10 different simultaneously running weeks of 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 days, of which the weeks of 4, 8, and 9 days are interrupted to fit into the 210-day cycle.

Modern calendar reforms[edit]

The International Fixed Calendar (also known as the «Eastman plan») kept a 7-day week while defining a year of 13 months with 28 days each (364 days). Every calendar date was always on the same weekday. It was the official calendar of the Eastman Kodak Company for decades.

A 10-day week, called a 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.

The Bahá’í calendar features a 19-day period which some classify as a month and others classify as a week.^[60]

Soviet calendar[edit]

In the Soviet Union between 1929 and 1940, most factory and enterprise workers, but not collective farm workers, used five and six day work weeks while the country as a whole continued to use the traditional seven day week.^[61][62][63]

From 1929 to 1951, five national holidays were days of rest (22 January, 1–2 May, 7–8 November). From autumn 1929 to summer 1931, the remaining 360 days of the year were subdivided into 72 five day work weeks beginning on 1 January. Workers were assigned any one of the five days as their day off, even if their spouse or friends might be assigned a different day off. Peak use of the five day work week occurred on 1 October 1930 at 72% of industrial workers. From summer 1931 until 26 June 1940, each Gregorian month was subdivided into five six day work weeks, more-or-less, beginning with the first day of each month. The sixth day of each six day work week was a uniform day of rest. On 1 July 1935 74.2% of industrial workers were on non-continuous schedules, mostly six day work weeks, while 25.8% were still on continuous schedules, mostly five day work weeks. The Gregorian calendar with its irregular month lengths and the traditional seven day week were used in the Soviet Union during its entire existence, including 1929–1940; for example, in the masthead of Pravda, the official Communist newspaper, and in both Soviet calendars displayed here. The traditional names of the seven day week continued to be used, including «Resurrection» (Воскресенье) for Sunday and «Sabbath» (Суббота) for Saturday, despite the government’s official atheism.

Irregular weeks[edit]

The «Hermetic Lunar Week Calendar»^[64] is a strictly lunar calendar, apparently proposed to illustrate the complications of astronomically based calendars. Its unique feature is irregular-length «weeks» which average approximately 7+3⁄8 days each. The weeks are fixed by the astronomical phases of the moon; the last day of the week fixed to coincide with a new-moon, first quarter-moon, full-moon, or third quarter-moon. Although typical months have three weeks of 7 days and one week of 8 days (29 day month) or two weeks of 7 days and two weeks of 8 days (30 day month), due to variations in the moon’s orbit, the weeks in the Hermetic calendar range 6–9 days.^[64]

See also[edit]

• Determination of the day of the week
• GPS week number
• Names of the days of the week
• Workweek and weekend

Notes[edit]

References[edit]

• Zerubavel, Eviatar (1989). The Seven Day Circle: The History and Meaning of the Week. University of Chicago Press. ISBN 978-0-226-98165-9.

Further reading[edit]

• Colson, Francis Henry (1926). The Week: An Essay on the Origin and Development of the Seven-day Cycle. Cambridge University Press. OCLC 59110177.
• Thomas, Northcote Whitridge (1911). «Week» . In Chisholm, Hugh (ed.). Encyclopædia Britannica. Vol. 28 (11th ed.). Cambridge University Press. p. 466.

Last Updated:
11 Apr 2023
— Updated example sentences

week

a period of seven days: It has been a week since I saw him.

Not to be confused with:

weak – not strong; feeble; lacking firmness or force of will: The illness had made her weak.

Abused, Confused, & Misused Words by Mary Embree Copyright © 2007, 2013 by Mary Embree

week

 (wēk)

n.

1.

a. A period of seven days: a week of rain.

b. A seven-day calendar period, especially one starting with Sunday and continuing through Saturday: this week.

2.

a. A week designated by an event or holiday occurring within it: commencement week.

b. A week dedicated to a particular cause or institution: Home Safety Week.

3. The part of a calendar week devoted to work, school, or business: working a three-day week.

4.

a. One week from a specified day: I’ll see you Friday week.

b. One week ago from a specified day: It was Friday week that we last met.

---

American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

week

(wiːk)

n

1. a period of seven consecutive days, esp one beginning with Sunday.

2. a period of seven consecutive days beginning from or including a specified day: Easter week; a week from Wednesday.

3. (Industrial Relations & HR Terms) the period of time within a week devoted to work

4. a week devoted to the celebration of a cause

adv

chiefly Brit seven days before or after a specified day: I’ll visit you Wednesday week.

[Old English wice, wicu, wucu; related to Old Norse vika, Gothic wikō order]

Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014

week

(wik)

n.

1. a period of seven successive days, usu. 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.

3. (often cap.) a period of seven successive days devoted to celebrating or honoring something: National Book Week.

4. the working portion of the seven-day period; workweek: a 35-hour week.

adv.

5. seven days before or after a specified day: I shall come Tuesday week.

[before 900; Middle English weke, Old English wice, c. Old Saxon crūcewika Holy Week, Old High German wehha, Old Norse vika week, Gothic wikō turn]

Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.

week

A week is a period of seven days. A week is usually regarded as beginning on a Monday, or sometimes on a Sunday.

She will be back next week.

It will take several weeks to repair the damage.

If something happens in the week or during the week, it happens on weekdays, which are the days when people usually go to work or school, rather than at the weekend.

In the week, we get up at seven.

I never have time to cook during the week.

Collins COBUILD English Usage © HarperCollins Publishers 1992, 2004, 2011, 2012

Translations

• Abkhaz: амчыбжь (amčəbž)
• Adyghe: тхьамафэ (tḥaamaafe)
• Afar: ayam
• Afrikaans: week (af)
• Albanian: javë (sq) f
• American Sign Language: 1@BasePalm-PalmDown-OpenB@CenterChesthigh-PalmUp 1@Finger-PalmDown-OpenB@CenterChesthigh-PalmUp
• Amharic: ሳምንት (samnət)
• Arabic: أُسْبُوع‎ m (ʔusbūʕ), جُمْعَة‎ (ar) f (jumʕa)

  Egyptian Arabic: اسبوع‎ m (ʾesbūʿ)

  Gulf Arabic: إسبوع‎ m (ʾisbūʿ)

  Hijazi Arabic: أُسبوع‎ m (ʾusbūʿ)

  Moroccan Arabic: سيمانة‎ f (simāna), أُسبوع‎ m (ʾusbūʿ), سيمانة‎ (simāna)

  North Levantine Arabic: جمعة‎ (jimʿa)

• Aragonese: semana f
• Aramaic:

  Classical Syriac: ܫܒܘܥܐ‎, ܫܒܬܐ‎

• Armenian: շաբաթ (hy) (šabatʿ)
• Aromanian: siptãmãnã f, stãmãnã f, stãmene f
• Assamese: সপ্তাহ (xoptah)
• Asturian: selmana (ast) f, sermana f, semana (ast) f, semá f, sumana (ast) f
• Avar: анкь (ankkˡʼ)
• Azerbaijani: həftə (az)
• Bashkir: аҙна (aðna)
• Basque: aste (eu)
• Belarusian: ты́дзень (be) m (týdzjenʹ)
• Bengali: সপ্তাহ (bn) (śoptaho)
• Bhojpuri: 𑂮𑂣𑂹𑂞𑂰𑂯 (saptāh)
• Breton: sizhun (br) f
• Bulgarian: се́дмица (bg) f (sédmica)
• Burmese: ရက်သတ္တပတ် (my) (raksatta.pat), တစ်ပတ် (my) (tacpat)
• Buryat: долоон хоног (doloon xonog)
• Catalan: setmana (ca) f
• Cebuano: semana
• Chakma: please add this translation if you can
• Chechen: кӏира (kʼira)
• Cherokee: ᏑᎾᏙᏓᏆᏍᏗ (sunadodaquasdi)
• Chichewa: mlungu, sabata
• Chinese:

  Cantonese: 星期 (sing¹ kei⁴), 禮拜／礼拜 (lai⁵ baai³)

  Dungan: щинчи (xinči), чи (či)

  Hakka: 禮拜／礼拜 (lî-pai)

  Mandarin: 星期 (zh) (xīngqī), 週／周 (zh) (zhōu), 禮拜／礼拜 (zh) (lǐbài)

  Min Dong: 禮拜／礼拜 (lā̤-bái)

  Min Nan: 禮拜／礼拜 (zh-min-nan) (lé-pài)

  Wu: 星期 (xin qi), 禮拜／礼拜 (li pa)

• Chuvash: эрне (erne)
• Corsican: settimana f, sittimana f, simana f
• Crimean Tatar: afta
• Czech: týden (cs) m
• Dalmatian: jedma f, setemúna f, setimuón
• Danish: uge (da) c
• Dhivehi: ހަފްތާ‎ (haftā)
• Dutch: week (nl) f
• Emilian: stmèna
• Erzya: тарго (targo)
• Esperanto: semajno (eo)
• Estonian: nädal (et)
• Fala: semana
• Faroese: vika f
• Fijian: macava (fj)
• Finnish: viikko (fi)
• Franco-Provençal: semana
• French: semaine (fr) f, huit jours (fr)
• Friulian: setemane f
• Galician: semana (gl) f, semá (gl) f, semán (gl) f, somana (gl) f, domá f
• Georgian: კვირა (ka) (ḳvira)
• German: Woche (de) f
• Gilbertese: wiki
• Gothic: 𐍅𐌹𐌺𐍉 f (wikō)
• Greek: εβδομάδα (el) f (evdomáda), επταήμερο (el) n (eptaḯmero), εφταήμερο (el) n (eftaḯmero)

  Ancient: ἑβδομάς f (hebdomás)

• Guaraní: arapokõindy
• Gujarati: અઠવાડિયું n (aṭhavāḍiyũ)
• Haitian Creole: semèn
• Hausa: mako
• Hawaiian: pule
• Hebrew: שבוע / שָׁבוּעַ‎ (he) m (shavúa)
• Hindi: हफ़्ता (hi) m (haftā), सप्ताह (hi) m (saptāh), वीक (hi) m (vīk)
• Hungarian: hét (hu)
• Icelandic: vika (is) f
• Ido: semano (io)
• Inari Sami: okko
• Indonesian: minggu (id), pekan (id)
• Ingush: кӏира (kʼira)
• Interlingua: septimana (ia)
• Iranun: please add this translation if you can
• Irish: seachtain (ga) f
• Istro-Romanian: šetimana
• Italian: settimana (it) f
• Japanese: 週 (ja) (しゅう, shū), 週間 (ja) (しゅうかん, shūkan)
• Kalmyk: долан хонг (dolan hong)
• Kannada: ವಾರ (kn) (vāra)
• Karachay-Balkar: ыйыкъ (ıyıq)
• Karelian: nedali, nedäli
• Kashmiri: ہَفتہٕ‎ (haftụ)
• Kashubian: tidzéń (csb) m
• Kazakh: апта (kk) (apta), жұма (kk) (jūma)
• Khmer: សប្តាហៈ (sapphdaahaʼ), អាទិត្យ (km) (ʼaatɨt), សត្តាហៈ (sattaahaʼ), សប្តាហ៍ (sappədaa)
• Komi-Permyak: недель (ňeďeľ), вежон (vežon)
• Komi-Zyrian: вежон (vežon)
• Korean: 주(週) (ko) (ju), 주일(週日) (ko) (ju’il)
• Kurdish:

  Central Kurdish: حەفتە‎ (ckb) (ḧefte)

  Northern Kurdish: heftê (ku)

• Kyrgyz: апта (ky) (apta), жума (ky) (juma), жетикүн (jetikün)
• Ladin: ena f, setemena f
• Ladino: semana, סימאנה‎
• Lak: нужмяр (nužmaˤr)
• Lao: ສັບດາ (sap dā), ສັບປະດາ (sap pa dā), ອາທິດ (lo) (ʼā thit), ສັດຕາຫະ (sat tā ha)
• Latgalian: nedeļa f
• Latin: hebdomas (la) f, septimāna f (Late)
• Latvian: nedēļa (lv) f
• Leonese: selmana
• Lezgi: гьафте (hafte)
• Limburgish: waek (li)
• Lindu: minggu
• Lithuanian: savaitė (lt) f
• Livonian: nädīļ
• Louisiana Creole French: lasmènn, smènn
• Low German:

  German Low German: Week (nds) f

• Luganda: sabbiiti
• Luxembourgish: Woch (lb) f
• Macedonian: седмица f (sedmica), недела (mk) f (nedela)
• Magahi: 𑂮𑂣𑂹𑂞𑂰𑂯 (saptāh)
• Maguindanao: saka padian
• Maithili: सप्ताह (saptāh), अठबार (aṭhᵊbār)
• Malay: minggu (ms) (Malaysia, Singapore), pekan (Riau), jemaat, jumaat (both obsolete)
• Malayalam: ആഴ്ച (ml) (āḻca)
• Maltese: ġimgħa
• Manchu: [script needed] (barun)
• Manx: shiaghtin f
• Maori: wiki
• Maranao: padiqan
• Marathi: आठवडा (mr) (āṭhavḍā)
• Mauritian Creole: semenn
• Megleno-Romanian: săptămănă f, săptămǫnă f, sămǫnă f, smǫnă f
• Middle Persian: 𐭤𐭯𐭲𐭪‎ (hptk /haftag/)
• Mirandese: sumana
• Moksha: недля (ńedľa), тарга (targa)
• Mongolian:

  Cyrillic: долоо хоног (doloo xonog), гариг (mn) (garig) (Inner Mongolia)

  Mongolian: ᠳᠣᠯᠤᠭ᠎ᠠ
  ᠬᠣᠨᠤᠭ (doluɣ’a qonug), ᠭᠠᠷᠠᠭ (ɣarag)

• Mòcheno: boch f
• Nahuatl: chicōntōnalli
• Nalca: minggu
• Navajo: damį́įgo, damóo
• Navarro-Aragonese: semana
• Neapolitan: semmana f, semana f
• Nepali: हप्‍ता (hapatā)
• Ngazidja Comorian: mfumo class 3/4
• Norman: s’maine f (Jersey), s’môine f (Guernsey)
• North Frisian: weg f
• Northern Sami: vahkku
• Norwegian:

  Bokmål: uke (no) m or f

  Nynorsk: veke f, vika f (archaic, Høgnorsk)

• Occitan: setmana (oc) f
• Ojibwe: anamiʼe-giizhik
• Old Church Slavonic:

  Cyrillic: седмица f (sedmica)

• Old East Slavic: тꙑижьдьнь f (tyižĭdĭnĭ), тꙑжьдьнь m (tyžĭdĭnĭ)
• Old English: wiċe f
• Old French: semeine f, semaine f
• Old Norse: vika f
• Old Saxon: wika f
• Oriya: ସପ୍ତାହ (sôptahô)
• Oromo: torbee
• Ossetian: къуыри (k’°yri)
• Papiamentu: siman
• Pashto: اونۍ‎ f (onə́y)
• Persian: هفته‎ (fa) (hafte)
• Piedmontese: sman-a
• Plautdietsch: Wäakj f
• Polish: tydzień (pl) m inan
• Portuguese: semana (pt) f
• Punjabi: ਹਫ਼ਤੇ (hafte)
• Quechua: simana (qu), hunk’a, qanchischaw
• Rohingya: hafta
• Romagnol: stmana f
• Romani: kurko m
• Romanian: săptămână (ro) f
• Romansch: emna f, emda f, jamna f, eamda
• Russian: неде́ля (ru) f (nedélja)
• Rusyn: ты́ждень m (tŷ́ždenʹ)
• Sabir: settimana
• Saho: liggidina
• Samoan: vaiaso
• Sardinian: chída f, chida f, chita f, cida f, cira f
• Scottish Gaelic: seachdain f
• Serbo-Croatian:

  Cyrillic: недеља f, нѐдјеља f, нѐђеља f, те̏дан m, тје̏дан m, сѐдмица f

  Roman: nèdelja (sh) f, nèdjelja (sh) f, nèđelja (sh) f, tȅdan m, tjȅdan (sh) m, sèdmica (sh) f

• Seychellois Creole: semenn
• Sicilian: simana (scn) f
• Silesian: tydźyń m
• Sinhalese: සතිය (si) (satiya)
• Skolt Sami: neäʹttel
• Slovak: týždeň (sk) m
• Slovene: téden (sl) m
• Somali: toddobaad
• Sorbian:

  Lower Sorbian: tyźeń m

  Upper Sorbian: tydźeń (hsb) m

• Southern Sami: våhkoe
• Spanish: semana (es) f

  Old Spanish: semana, setmana

• Sranan Tongo: wiki
• Swahili: wiki (sw), juma
• Swedish: vecka (sv) c
• Sylheti: please add this translation if you can
• Tagalog: linggo (tl), semana
• Tahitian: hepetoma
• Tajik: ҳафта (tg) (hafta)
• Tamil: கிழமை (ta) (kiḻamai), வாரம் (ta) (vāram)
• Taos: tumį́ku
• Tarantino: sumáne f, sumana f
• Tatar: атна (tt) (atna)
• Tausug: pitu
• Telugu: వారము (te) (vāramu)
• Thai: สัปดาห์ (th) (sàp-daa), อาทิตย์ (th) (aa-tít), สัตวาร, สัตตาห
• Tibetan: བདུན་ཕྲག (bdun phrag)
• Tigrinya: ሰሙን (sämun)
• Tok Pisin: wik
• Tswana: beke
• Turkish: hafta (tr), yedil (tr)
• Turkmen: hepde
• Tuvan: чеди хонук (çedi xonuk), неделя (nedelya), чедилик (çedilik)
• Udi: шаматӏ (šamaṭ)
• Udmurt: арня (arňa)
• Ukrainian: ти́ждень (uk) m (týždenʹ)
• Urdu: ہفتہ‎ (ur) m (haftā), سپتاہ‎ m (saptāh)
• Uyghur: ھەپتە‎ (hepte)
• Uzbek: hafta (uz)
• Venda: vhege
• Venetian: setimana (vec) f, stemana f, stimana f, setemana f
• Vietnamese: tuần (vi), tuần lễ (vi)
• Volapük: vig (vo)
• Walloon: samwinne (wa) f, samaîun
• Welsh: wythnos (cy) f
• West Frisian: wike (fy) c
• White Hmong: lis tiam
• Wolof: ayubés, besboai
• Xhosa: veki
• Yagnobi: ҳафта (hafta)
• Yakan: please add this translation if you can
• Yakut: нэдиэлэ (nediele)
• Yao: ci-juma
• Yiddish: וואָך‎ (yi) f (vokh)
• Yoruba: ọ̀sẹ̀
• Zazaki: hefte (diq)
• Zhuang: singhgiz, singgeiz, lijbai, cou
• Zulu: iviki (zu)
• ǃXóõ: bìikì