As the days pass, the cycle of the week shapes how we live our lives. Have you ever wondered, “Why is a week seven days long?” How about where the names of each weekday come from?
The seven-day week originates from the calendar of the Babylonians, which in turn is based on a Sumerian calendar dated to 21st-century B.C. Seven days corresponds to the time it takes for a moon to transition between each phase: full, waning half, new and waxing half. Because the moon cycle is 29.53 days long, the Babylonians would insert one or two days into the final week of each month.
Jewish tradition also observes a seven-day week. The book of Genesis (and hence the seven-day account of creation) was likely written around 500 B.C. during the Jewish exile to Babylon. Assyriologists such as Friedrich Delitzsch and Marcello Craveri have suggested that the Jews inherited the cycle of seven days from the Babylonian calendar.
The Romans also inherited this system from Babylonian tradition, though they didn’t begin using it until the instatement of the Julian Calendar in the first-century B.C. Up until this point the Romans had used the “nundinal cycle,” a system they inherited from the Etruscans. This was a market cycle of eight days labeled A-H. On market day, country folk would come to the city and city dwellers would buy eight days’ worth of groceries. By the time the seven-day week was officially adopted by Constantine in A.D. 321, the nundinal cycle had fallen out of use.
The Seven-Day Week
The Babylonians marked time with lunar months. They proscribed some activities during several days of the month, particularly the-
- First – The first visible crescent
- Seventh – The waxing half moon
- Fourteenth – The full moon
- Nineteenth – Dedicated to an offended goddess
- Twenty-first – The waning half moon
- Twenty-eight – The last visible crescent
- Twenty-ninth – The invisible moon
- Thirtieth(possibly) – The invisible moon
The major periods are seven days, 1/4 month, long. This seven-day period was later regularised and disassociated from the lunar month to become our seven-day week.
The Naming of the Days
The Greeks named the days week after the sun, the moon and the five known planets, which were in turn named after the gods Ares, Hermes, Zeus, Aphrodite, and Cronus. The Greeks called the days of the week the Theon hemerai “days of the Gods”. The Romans substituted their equivalent gods for the Greek gods, Mars, Mercury, Jove (Jupiter), Venus, and Saturn. (The two pantheons are very similar.) The Germanic peoples generally substituted roughly similar gods for the Roman gods, Tiu (Twia), Woden, Thor, Freya (Fria), but did not substitute Saturn.
Sunday – Sun’s Day
The name “Sunday”, the day of the Sun, is derived from Hellenistic astrology, where the seven planets, known in English as Saturn, Jupiter, Mars, the Sun, Venus, Mercury and the Moon, each had an hour of the day assigned to them, and the planet which was regent during the first hour of any day of the week gave its name to that day. During the 1st and 2nd century, the week of seven days was introduced into Rome from Egypt, and the Roman names of the planets were given to each successive day.
Germanic peoples seem to have adopted the week as a division of time from the Romans, but they changed the Roman names into those of corresponding Teutonic deities. Hence, the dies Solis became Sunday (German, Sonntag).
The English noun Sunday derived sometime before 1250 from sunedai, which itself developed from Old English (before 700) Sunnandæg (literally meaning “sun’s day”), which is cognate to other Germanic languages, including Old Frisian sunnandei, Old Saxon sunnundag, Middle Dutch sonnendach (modern Dutch zondag), Old High German sunnun tag (modern German Sonntag), and Old Norse sunnudagr (Danish and Norwegian søndag, Icelandic sunnudagur and Swedish söndag). The Germanic term is a Germanic interpretation of Latin dies solis (“day of the sun”), which is a translation of the Ancient Greek heméra helíou. The p-Celtic Welsh language also translates the Latin “day of the sun” as dydd Sul.
In most Indian languages, the word for Sunday is Ravivāra or Adityavāra or its derived forms — vāra meaning day, Aditya and Ravi both being a style (manner of address) for Surya i.e. the Sun and Suryadeva the chief solar deity and one of the Adityas. Ravivāra is first day cited in Jyotisha, which provides logical reason for giving the name of each week day. In the Thai solar calendar of Thailand, the name (“Waan Arthit”) is derived from Aditya, and the associated colour is red.
Monday – Moon’s Day
The names of the day of the week were coined in the Roman era, in Greek and Latin, in the case of Monday as ἡμέρᾱ Σελήνης, diēs Lūnae “day of the Moon”. Many languages use terms either directly derived from these names, or loan-translations based on them. The English noun Monday derived sometime before 1200 from monedæi, which itself developed from Old English (around 1000) mōnandæg and mōndæg (literally meaning “moon’s day”), which has cognates in other Germanic languages, including Old Frisian mōnadeig, Middle Low German and Middle Dutch mānendag, mānendach (modern Dutch Maandag), Old High German mānetag (modern German Montag), and Old Norse mánadagr (Swedish and Norwegian nynorsk måndag, Icelandic mánudagur. Danish and Norwegian bokmål mandag). The Germanic term is a Germanic interpretation of Latin lunae dies (“day of the moon”).
In many Indo-Aryan languages, the word for Monday is Somavāra or Chandravāra, Sanskrit loan-translations of “Monday”.
Tuesday – Mars’s Day
The name Tuesday derives from the Old English “Tiwesdæg” and literally means “Tiw’s Day”. Tiw is the Old English form of the Proto-Germanic god *Tîwaz, or Týr in Old Norse. *Tîwaz derives from the Proto-Indo-European base *dei-, *deyā-, *dīdyā-, meaning ‘to shine’, whence comes also such words as “deity”.
The Latin name dies Martis (“day of Mars”) is equivalent to the Greek ἡμέρα Ἄρεως (Iméra Áreos). In most languages with Latin origins (Italian, French, Spanish, Catalan, Romanian, Galician, Sardinian, Corsican, but not Portuguese), the day is named after Mars, the Ancient Greek Ares Ἄρης .
In the Indo-Aryan languages Pali and Sanskrit the name of the day is taken from Angaraka (‘one who is red in colour’) a style (manner of address) for Mangala, the god of war, and for Mars, the red planet.
Wednesday – Mercury’s Day
The name Wednesday continues Middle English Wednesdei. Old English still had wōdnesdæg, which would be continued as *Wodnesday (but Old Frisian has an attested wednesdei). By the early 13th century, the i-mutated form was introduced unetymologically.
In most of the languages of India, the word for Wednesday is Budhavāra — vāra meaning day and Budha being the planet Mercury.
Thursday – Jupiter’s Day
The name is derived from Old English Þūnresdæg and Middle English Thuresday (with loss of -n-, first in northern dialects, from influence of Old Norse Þórsdagr) meaning “Thor’s Day”. It was named after the Norse god of Thunder, Thor.
In most Romance languages, the day is named after the Roman god Jupiter, who was the god of sky and thunder. In Latin, the day was known as Iovis Dies, “Jupiter’s Day”. In Latin, the genitive or possessive case of Jupiter was Iovis/Jovis and thus in most Romance languages it became the word for Thursday: Italian giovedì, Spanish jueves, French jeudi, Sardinian jòvia, Catalan dijous, Galician xoves and Romanian joi. This is also reflected in the p-Celtic Welsh dydd Iau.
In most of the languages of India, the word for Thursday is Guruvāra – vāra meaning day and Guru being the style for Bṛhaspati, guru to the gods and regent of the planet Jupiter. In Sanskrit language, the day is called Bṛhaspativāsaram (day of Bṛhaspati).
Friday – Venus’s Day
The name Friday comes from the Old English Frīġedæġ, meaning the “day of Frige”, a result of an old convention associating the Germanic goddess Frigg with the Roman goddess Venus, with whom the day is associated in many different cultures. The same holds for Frīatag in Old High German, Freitag in Modern German, and vrijdag in Dutch.
In most Indian languages, Friday is Shukravāra, named for Shukra, the planet Venus. In Bengali শুক্রবার or Shukrobar is the 6th day in the Bengali week of Bengali Calendar and is the beginning of the weekend is Bangladesh.
Saturday – Saturn’s Day
Between the 1st and 3rd centuries AD, the Roman Empire gradually replaced the eight-day Roman nundinal cycle with the seven-day week. The astrological order of the days was explained by Vettius Valens and Dio Cassius (and Chaucer gave the same explanation in his Treatise on the Astrolabe). According to these authors, it was a principle of astrology that the heavenly bodies presided, in succession, over the hours of the day. The association of the weekdays with the respective deities is thus indirect, the days are named for the planets, which were in turn named for the deities.
The Germanic peoples adapted the system introduced by the Romans but glossed their indigenous gods over the Roman deities in a process known as interpretatio germanica. In the case of Saturday, however, the Roman name was borrowed directly by West Germanic peoples, apparently because none of the Germanic gods were considered to be counterparts of the Roman god Saturn. Otherwise Old Norse and Old High German did not borrow the name of the Roman god (Icelandic laugardagur, German Samstag).
In most languages of India, Saturday is Shanivāra, vāra meaning day, based on Shani, the Vedic god manifested in the planet Saturn. In the Thai solar calendar of Thailand, the day is named from the Pali word for Saturn, and the color associated with Saturday is purple.