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Days of the Week: Origin of Their Names

Words can be enormously interesting! Alun has written several web articles about the origins of some very familiar English names and words.

The stories behind the names of the days of the week are interesting. Read on to learn more!

The stories behind the names of the days of the week are interesting. Read on to learn more!

Calendar Conversation

They are among the most commonly used words in the English language. They are the yardsticks by which we define the turning of the Earth on its axis, and the revolution of the Earth around the Sun. They are the words we use to date the events of history, and our lives. They are the seven days of the week and the twelve months of the year. But why seven days? And where do the very names themselves come from?

The English Names of the Days

1) SUNDAY - Sun's Day. Germanic translation of the Roman 'Day of the Sun'.

2) MONDAY - Moon's Day. Germanic translation of the Roman 'Day of the Moon'.

3) TUESDAY - Tyr's Day. Named for the Norse / Teutonic God.

4) WEDNESDAY - Woden's Day. Named for the Norse / Teutonic God.

5) THURSDAY - Thor's Day. Named for the the Norse / Teutonic God.

6) FRIDAY - Freya's Day. Named for the Norse / Teutonic Goddess.

7) SATURDAY - Saturn's Day. Germanic translation of the Roman 'Day of Saturn'.

Why Are There Seven Days in a Week?

The number of days in the week has not always been seven in all societies. The early Egyptians had a 10-day week, as did briefly the French Revolutionary Government two hundred years ago. An ancient calendar once used in Lithuania employed a nine-day week, whilst the Mayans of Central America used a complicated system including 'weeks' of 13 numbered days and 'weeks' of 20 named days. As recently as 1930, the Soviet Union toyed with the idea of a five-day week.

The point about this is that a week—unlike a year (one complete revolution of the Earth around the Sun), or a day (one complete rotation of the Earth on its axis)—has no scientific basis; there is no astronomical event pertaining to a week, much less a week of seven days.

However the number seven did hold a sacred significance for many societies in which ritual was of great importance. The lunar month was approximately 28 days long (easily divisible into four quarters or phases of the moon, each of seven days), and in the sky, there were seven traditionally identified planets. Both of these factors contributed at different times to the adoption and proliferation of the seven-day week as we shall see. Later on, the seven-day creation myth of the burgeoning Christian religion cemented the length of the week in most Western civilisations,

It seems that ancient Babylon was possibly the first civilisation to divide the year in this way, and it seems it was the length of the lunar month which was most important to this society. The phases of the lunar cycle —New Moon, waxing half Moon, Full Moon, and waning Half Moon—were obvious visual signs which could be interpreted in a religious or astrological way. Certain activities and festivals became set by the phases of the Moon, and hence by the days of a seven-day week.

This was later adopted by the Greek and Roman Empires, and then the Christian religion. As Christian European nations developed empires throughout the world, the seven-day week became the established norm.

How the Days of the Week Came into Being

The Babylonians chose to assign each of the days in their week to one of the recognised seven planets of antiquity. This same system was later adopted by the Greeks and Romans. The Greeks deified these planets with the names of Gods, and this practice was continued by the Romans who substituted their own Gods (each designated with a planetary name) for their Greek counterparts. Hence, they named the seven days after Mars, Mercury, Jupiter, Venus, and Saturn, as well as the Moon and the Sun (originally thought of as planets).

The new Christian religion began to wield an influence in these matters in the 3rd and 4th centuries AD. Initially, the Romans had had Saturday as the first day of the week, but the first Christian Emperor of Rome, Constantine, decreed that Sunday would become the first day. Sunday also gained favour as the Sabbath in the Christian religion as this clearly separated the religion from the traditions of the Jewish Sabbath on a Saturday. The concept of Sunday as both the first day and the Sabbath took root and remains so to the current day (though the modern working practice of a five-day week and a weekend means that there is a growing inclination to regard Monday as the first day).

With the decline of the Roman Empire, a clear division between the cultures of Latin Europe and Northern Germanic Europe took place. In much of Latin-influenced Europe - particularly Spain, Italy and France—the original Roman God-Planet designations for the days survive in the names of the days today, as we can see in the next section. However, in Northern Europe, another set of influences came to bear, as the Germanic tribes inhabiting the area chose to rename some of the days according to their own Teutonic and Norse religions and cultures. Three of the days—the days of the Sun, the Moon and Saturn—were retained and more or less simply translated from the Roman, but on the other four days, their own Gods were substituted for the Roman equivalents, just as the Romans had previously done to the Greek and Babylonian systems.

The true significance of this linguistic adjustment, came about when Germanic tribes—the Angles, Jutes and Saxons—invaded the land of Britain during the Dark Ages. They brought with them the Anglo-Saxon language and the origins of English.

The Development of the English Names of Days

In this section, I look at the detailed linguistic origins of the English names of each day of the week. For this purpose, there are three important areas of influences;

1) The Latin influence (The Roman Empire)

2) The Germanic and Norse influence (Anglo-Saxons)

3) Old English (450-1100AD) and Middle English (1100-1500AD)

  • SUNDAY - This day was designated in early Roman Latin as 'dies Solis', or 'Day of the Sun', but in later Latin this became 'Dominica', 'Day of God'. This word was to become the stem of most Latin languages, such as Spanish (Domingo) and Italian (Domenica). However in Northern Europe the Germanic tribes adopted the older idea of the Sun's Day, and simply translated this into their own languages. Thus the Old Germanic 'Sunnon-dagaz' became 'Sonntag' in Modern German, and 'Zondag' in Modern Dutch. In Old English, 'Sunnandaeg' developed into Middle English 'Sunnenday', and ultimately the Modern English 'Sunday'.
  • MONDAY - Monday's origins throughout the European languages, is very similar to Sunday's. Like Sunday, Monday was named by the Romans after a Heavenly body, in this case the Moon. The Latin term was 'dies Lunae' or 'Day of the Moon'. Again, like Sunday, the Latin term would influence modern languages such as Spanish (Lunes), Italian (Lunedi) and French (Lundi). However in Northern Europe, the Old Germanic translation of 'Mani' or Moon Day was to become established. So, in Modern German and Dutch, 'Montag' and 'Maandag' have obviously similar roots to the English name. The Anglo-Saxon name was 'Mondaeg' - very close to the Modern English 'Monday'.
  • TUESDAY - The next four days of the week are all derived from Norse God substitutes for their Roman counterparts. Thus in the Roman world Tuesday was dedicated to the Roman God of War, Mars, and was known as 'dies Martis', which has given us the Spanish (Martes) the Italian (Martedi) and the French (Mardi), but in the Germanic / Norse world Tuesday was re-named after Tyr, the Norse God of War.The Germanic version of Tyr was Tiw, or Tiu, and therefore when the tribes invaded Britain, the day became Tiwesdaeg. In the Middle Ages this became 'Tiwesday' or Tiu's Day, and later 'Tuesday'.
  • WEDNESDAY - Wednesday was originally named for the Roman Messenger of the Gods, Mercury, and known as 'Dies Mercurii'. This gave the Italian language (Mercoledi) and the French (Mercredi). However, like Tuesday, the Northern tribes substituted a God of their own - Odin (Norse) or Woden (Germanic) - the Supreme God of Teutonic theology. The Old English 'Wednesdaeg' was a corruption of 'Wodnesdaeg' or Woden's Day. This became Wednesdai (y) in the Middle Ages, and later 'Wednesday'.
  • THURSDAY - Thursday was originally named for the supreme Roman God, Jove, or Jupiter. 'Dies Jovis' was adapted for other Latin languages such as Spanish (Jueves), The Northern Germanic tribes chose to substitute their God Thor, in the naming of the day. This name came to Anglo-Saxon Britain as 'Thursdaeg' or Thor's Day, later developing into 'Thursday'.
  • FRIDAY - Friday was originally named by the Romans after Venus, the God of Love, and called 'Dies Veneris'. This gives the stem of the Spanish (Viernes), the Italian (Venerdi), and the French (Vendredi). Again, the Germanic tribes installed their own equivelant Goddess for this day. They chose Frigg or Freya, Norse and Teutonic Goddesses of Love. The day has come down to us in Modern German as 'Freitag'. When the Angles and Saxons invaded Britain, 'Frigedaeg' or Freya's Day of the Old English language developed into 'Fridai' in the Middle Ages, and eventually this became 'Friday'.
  • SATURDAY - Saturday is Saturn's Day, named after the Roman God of time and the harvest and known to the Romans as 'Dies Saturni'. This day, like Sunday and Monday, (but unlike Tuesday, Wednesday, Thursday or Friday) was simply modified by the Germanic languages without substitution of one of their own Gods. Thus, the Anglo-Saxon 'Sater-daeg', or 'Saternesdaeg' which both have clear Roman roots, developed into Middle English 'Saterdai' and then 'Saturday'.


Felix on November 15, 2019:

Thank you for this wonderful explanation, well written informative explanation on the week and months historical lineage. I have searched several pages and this one by far, in my opinion, is the best written and organized. Beautiful done! ~ Felix

Kravin on September 21, 2018:


Nice and informative article

Could you please shed any light on why the names are in the existing order

For eg

Why is Sunday followed by Monday, which is followed by Tuesday

Many thanks


Greensleeves Hubs (author) from Essex, UK on November 09, 2014:

klidstone1970; Thanks Kim. It is, I agree, quite fascinating how words develop, and particularly how in this case, different days of the week have experienced different influences in their naming - some directly relating to Roman gods and some being modified to pay homage to Norse / Germanic gods. Appreciate your visit very much Kim

இڿڰۣ-- кιмвєяℓєу from Niagara Region, Canada on November 05, 2014:

Quite fascinating how with time, the names evolved in what we know today. Your inclusion of the written and spoken word and how it was influenced is really quite interesting, Alun. Nice job. Kim.

Greensleeves Hubs (author) from Essex, UK on November 25, 2013:

Thanks Thief12. I wrote this page principally because these are words which are so familiar to us, (quite literally used every day) and yet their origins are unknown to most - including me, before I researched the subject!

Carlo Giovannetti from Puerto Rico on November 25, 2013:

Really interesting. Never really knew why they gave them those names.

Greensleeves Hubs (author) from Essex, UK on June 02, 2012:

Thank you Nishat. I'm sure the main reason for the 7 days in a week is because the 7 day gaps between the 4 quarters of the Moon from New through Half Moon to Full and back again to New, were easily recognisable and provided a means for dividing the year. But the other factors mentioned probably also played a part. Cheers for visiting and commenting! Alun.

Nishat on June 02, 2012:

Hey, thought I'd check your website out again and this page is really very interesting, I always wondered why there were 7 days in a week. :)

Greensleeves Hubs (author) from Essex, UK on November 09, 2011:

Derdriu thanks for visiting. It is interesting that the French had no major input into the English words for the days of the week (or months of the year). I think the French influence (Battle of Hastings/1066 and all that) came just a bit too late. By that stage I guess the Anglo Saxon names were too well established, and it would have been hard for the minority Norman rulers to impose their own words on the majority Saxons to replace such familiar words as the days of the week.

Thanks for your comments as always. Alun

Derdriu on November 07, 2011:

Alun/Greensleeves Hubs: It is most helpful the way in which you start with the possible origins of the number of days in a week. With the easier hurdle out of the way, it is more comfortable for the reader to process the more convoluted origins of the names of the seven days. It is interesting that each name has similar inspirations in Latin, Old Germanic and Norse, with the exception being Wednesday.

Thank you, voted up, etc.,


P.S. Isn't it surprising that 300 years of French-speaking kings between the 11th and the 13th centuries resulted in the assimilation of quite a few words, but not the days of the week?

Greensleeves Hubs (author) from Essex, UK on May 02, 2011:

Thanks Daydreamer.

Daydreamer Too on April 30, 2011:

Very interesting and fact filled, thanks.

Greensleeves Hubs (author) from Essex, UK on April 30, 2011:

THanx for your comment. Appreciated.

StrictlyQuotes from Australia on April 29, 2011:

That's really interesting information! Thanks!