Saturn and Saturday

I just noticed that Saturn and Saturday (both named for the same fellow, in English) and likewise similar in Japanese, do-sei and do-youbi. I love etymology but don’t know how to pursue it in Japanese since my skills aren’t up there–does anyone know if Japanese simply adopted our English words, and came up with a Japanese equivalent, or is this a coincidence? (Saturn’s a primordial titan, so the “dirt day” or “dirt planet” sort of make sense …)

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Not exactly clear, but I think the names of the week are/were based on the order of the planets in both language( familie)s. So that is the overlap.

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There was certainly no connection to English, given the history. Anyway. I searched for an answer and found this:

" Note that the first five planets’ names (excluding Earth) are associated with the five elements. These five classical elements are called Wǔ Xíng in Chinese, they are namely water, metal, fire, wood and earth. Wu Xíng is applied to the concept of phenomena like time, space and existence. Mercury, Venus, Mars, Jupiter and Saturn being close to the Earth, exert their influence on life on our planet. Hence, Wu Xíng elements are assigned to all the five planets that astrologically affect the Earth.

In many parts of the world, days of the week are named after the sun, moon and planets. Similarly, the Chinese names for days of the week are also associated with the five above mentioned planets, the sun and the moon. All these seven celestial bodies are visible to the naked eye, from the surface of the Earth.

The Japanese names of the planets as well the days of the week are 漢語 kango or words of Chinese origin. "

Not sure, how valid the source is though:


I was told by my Japanese colleague (HS teacher) that Japanese adopted the French system of naming the days of the week after particular celestial bodies (knowing French helped me remember the Japanese more easily).

Mon - lundi - moon
Tue - mardi - Mars
Wed - mecredi - Mercury
Thur - jeudi - Jupiter
Fri - vendredi - Venus
Sat - samedi - Saturn

EDIT: the days do match the French, but correct reasons why are below


These guys give quite an interesting history of it all


That doesn’t seem very plausible. The words for the days were taken from Chinese and those words were in use long before French was ever a thing.


If you follow @denzo’s link, it states that the naming of the days of the week was done under pressure from the West, so it does make sense:

When they came under pressure to harmonise their working calendar with the West in the latter half of the 19th century, the Japanese turned to this old system to name the days of the week, officially adopting them in 1876.

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I read the link. It even states:

Although there were several routes of transmission into China, it appears that the Indian route was the direct source of the Japanese names for days of the week. In 806, the famous Japanese monk, Kobo Daishi (弘法大師) (Note: Kobo Daishi) brought Bu Kong’s writings back to Japan along with a huge quantity of other Buddhist scriptures.

Maybe you are thinking of something related to the adoption of a Gregorian style calender? But the names were imported into Japanese predating that by nearly a millenia. The names of the week were imported during the Heian period. There’s no possible way French could be the source of the names.


But the system originated in China (400 AD), was transmitted to Japan in Japan (800 AD) and was in use by ~1000 AD.

It was just readopted under pressure from the west.


Sorry, I had read some additional info by following one of the links:

After the guchureki -style calendars (具注暦 guchūreki, see note) went out of use, for much of the second millennium the planetary names in Japan were mainly used in kanagoyomi (仮名暦, kanagoyomi), calendars in the kana script used by women. The kanagoyomi recorded only the planetary name for the first day of each month. It was not until 1873, with the adoption of the solar calendar from the West, that every day of the month came to be marked with the name of the day.

In March 1876, the Western-style week was decreed for public use, starting the following month. This meant that the seven-day week became a part of everyday life rather than just an astrological curiosity. However, it was many years before industry moved to the custom of taking Sunday as the day of rest.

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I’m not arguing that the actual names came from French (since they are obviously different), but the decision of which day of the week to name after which ‘planet’.

The fact that they are an identical match is surely not just coincidence. It made sense to me when my colleague told me.

EDIT: Okay, I understand now - the idea was dispersed from India to both the East and the West, thus the matching between French and Japanese (and a number of other cultures as well, I imagine). I wonder why my colleague would have thought it was more direct?

Tellingly, the Chinese ‘seven luminaries’ were arranged in the same order as the Indian planetary names for days of the week, not in the classic order of the Chinese five elements, which put water before fire.

(less skimming, more actual reading… )


The specific ordering of the 7 planets for days of the week seems to have existed in the Roman Empire even by AD 100, and gone to China via india (by AD 400).

So definitely not coincidence…

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Well… I’ve been looking for the same answer because I noticed the days were easier to remember if I switched my mind to french.

However, in France, I learned that the names of the days come from the mythology gods, not actually from the planets! This said, the names are the same. It kinda me me rethink. Which came first? And I have no idea.

monday = lundi from luna - a good match
tuesday = mardi from Mars the god of war and I guess fire related mischief - acceptable match
wednesday = mercredi from Mercure but I’m not sure what the relation to water is because he’s a trade god (merchandise must come from there too)
thursday = jeudi from jupiter god of thunder but I guess ruler for the heavens and responsible for the earth surface so wood is a bit of a stretch
friday (I think from Freya in english) = vendredi from venus goddess of love and beauty not much to do with gold that I can remember but I suppose love is gold, right?
saturday = samedi from saturne one of the first gods, the time keeper. Had something to do with agriculture. You need soil for that.
Sunday = dimanche which I remember really bothered my child self for not fitting in!

In the end, although associating the names to french make it easier for me to remember, it’s not really a good match either.

Since I’m from Brittany, I thought maybe they’d have stuck with the elements but no, the names also match the “stars” from latin, including sunday. So Japanese and Breton have that in common! They match even better. I was happy to read that my name is part of the word for friday/venus in breton and welsh: gwener. I learned something today!


Thank you so much! I find this stuff just fascinating, but I wasn’t sure how to search for it.

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