It seems like a pretty simple question at first; they're just names. Monday, Tuesday, Wednesday, and so on. But why? None of them sound like other English words. And why are the names so different in different languages? How did the French get jeudi when the English got Thursday?
When looking at the names of the week, it's easy to start noticing a pattern:
- Monday- The English word can be traced back to the Old English word "mon(an)dæg," literally meaning "day of the moon". The French word, lundi, seems unrelated, but can actually be traced back to the Latin name "dies lunae," which means, literally, "day of the moon."
- Tuesday- The English name can be traced back to the Old English word "tiwesdæg," which means "Tiu's day." Tiu is the Germanic/English version of the Norse god Tyr, the god of war and the sky. The French word, mardi, is derived from the Latin name "dies Martis," meaning "day of Mars." Mars is the Roman god of war.
- Thursday- The English word for Thursday can be traced back to the Old Norse word "thorsdagr," meaning "Thor's day." Thor is the Norse god of thunder and lightning. The French word, jeudi, can be traced back to the Latin name "dies Jovis," meaning "day of Jupiter." Jupiter is the Roman god of thunder and lightning.
- Friday- The English word for Friday can be traced back to the Old English word "frigedæg," meaning "Freya's day." Freya is the Teutonic goddess of love and beauty. The French word, vendredi, is derived from the Latin name "dies Veneris," meaning "Venus' Day." Venus is the Roman goddess of love and beauty.
It's true, not all of the names fit perfectly into this pattern. Wednesday is derived from "Woden's day" in English, and mercredi is means "day of Mercury" in French. Woden and Mercury are unrelated. However, there's enough similarity to raise the question of why they're like that. When did the Norse, Romans, and early Germanic tribes get together and decide to name the fifth day of every week after their respective thunder gods?
The answer is actually pretty simple. The Teutons were an Germanic tribe that migrated into Europe from Scandinavia. While the Teutons were making their way down from the north, the Roman empire was expanding up from the south. As you can see here (a map of Teuton invasions) and here (a map of the Holy Roman Empire), they had plenty of chance to bump into each other. The Teutons brought their gods, and the Romans brought theirs, and somewhere along the line they adopted the "same" names for the days of the week. The Teutons became Germans, who are in the same language family as English. The Romans became the Italians, Spanish, and French, who all share similar words for the days of the week.
This is a great example of the way language evolves. The seven-day week is as old as the Babylonians, but these almost-standardized names aren't. Even though the Teutons and Romans were warring much of their time together, they still had enough contact to subtly blend their cultures. Languages still borrow from each other like this all the time. Kindergarten is German, valise is French, and bizarre is Spanish, just to name a few examples in English. That borrowing and blending is why we today can't understand Old English, and why people 1000 years in the future will have a hard time understanding our English. Language, and the way we use it, is almost like a living being; constantly changing, evolving, borrowing, or outright stealing from the other organisms around it to suit its needs. And frankly I think that's just the coolest.
