Where the Days of the Week Get Their Names
You say the words dozens of times a week without thinking about them. Monday, Tuesday, Wednesday. They feel like they've always been there — a fixed feature of how time is labeled. In fact, each day of the week is named after a mix of ancient astronomy, Roman gods, and Norse mythology, and the pattern is genuinely interesting once you know it.
The seven-day week itself is old. It shows up in Mesopotamian and Jewish traditions thousands of years ago, and it spread through the Roman Empire and, later, through the reach of Christianity and Islam. The English names we use today are a specific mash-up: partly Latin-Roman, partly Germanic-Norse, filtered through Old English into modern spelling.
Here's what each day is actually named for.
Sunday: the Sun
The most straightforward one. Sunday is named after the Sun. In Latin, the day was *dies Solis* — literally "day of the Sun." The Germanic languages preserved this directly: Old English *Sunnandæg*, German *Sonntag*, Dutch *zondag*. All roads lead back to the Sun.
In many Romance languages, Sunday was later renamed as "the Lord's day" (Spanish *domingo*, French *dimanche*, Italian *domenica*), reflecting Christian influence on the Roman calendar. English, along with the Germanic branch generally, kept the older Sun-based name.
Monday: the Moon
Also straightforward. Monday is the Moon's day. Latin *dies Lunae*, Old English *Mōnandæg*, meaning "day of the Moon." The pattern is preserved almost everywhere: French *lundi*, Spanish *lunes*, Italian *lunedì* all come from *Luna*, the Latin word for Moon.
The pairing of Sun and Moon at the start of the week reflects an old astronomical scheme where the seven days were assigned to the seven "planets" visible to the naked eye (Sun, Moon, Mars, Mercury, Jupiter, Venus, Saturn). Those seven bodies became the naming basis for the whole week across many cultures.
Tuesday: Tyr, the Norse god of war
Here's where the English names start diverging from Latin. In Latin, Tuesday was *dies Martis* — the day of Mars, the Roman god of war. When Germanic peoples adopted the Roman week, they translated the god names into their own mythology. Mars became Tyr (also spelled Týr or Tiw), the Norse and Anglo-Saxon god of war.
The Old English name *Tīwesdæg* — "Tiw's day" — became modern Tuesday. You can still see the Latin version in Romance languages: French *mardi*, Spanish *martes*, Italian *martedì*, all from Mars.
Wednesday: Odin
Wednesday continues the pattern. In Latin, this was *dies Mercurii* — the day of Mercury, the messenger god. In Germanic translation, Mercury became Woden or Odin, the chief god of Norse and Anglo-Saxon mythology.
Old English *Wōdnesdæg* — "Woden's day" — became modern Wednesday, which is why the spelling has that famously silent "d" in the middle. Romance languages kept the Mercury version: French *mercredi*, Spanish *miércoles*, Italian *mercoledì*.
Wednesday's association with Odin is one of the clearest cultural inheritances in the English language. Every time you say the word, you're reciting an old Anglo-Saxon devotional to a Norse god.
Thursday: Thor
The pattern continues. In Latin, Thursday was *dies Iovis* — the day of Jupiter, king of the Roman gods, associated with thunder and the sky. In Germanic mythology, the god of thunder was Thor, so translation was easy: Jupiter's day became Thor's day.
Old English *Þūnresdæg* (later spelled Thunresdæg) means "Thunor's day" — Thunor being the Anglo-Saxon variant of Thor. Modern Thursday preserves this directly. Romance languages: French *jeudi*, Spanish *jueves*, Italian *giovedì*, all from Jupiter.
Friday: Freya (or Frigg)
Friday, in Latin, was *dies Veneris* — the day of Venus, the goddess of love. In Germanic mythology, the closest equivalent was Freya (or possibly Frigg — historians debate which of the two Norse goddesses the day was actually named for; both are associated with love and beauty).
Old English *Frīgedæg* — "Frige's day" — became modern Friday. Romance languages preserved Venus: French *vendredi*, Spanish *viernes*, Italian *venerdì*.
Saturday: Saturn (the exception)
Saturday breaks the Germanic-translation pattern. In Latin, it was *dies Saturni* — the day of Saturn, the god of agriculture and time. Unlike the other Roman gods on this list, Saturn had no direct Germanic equivalent, so Anglo-Saxon speakers kept the Latin name.
Old English *Sæternesdæg* is basically just "Saturn's day," and modern Saturday is a lightly-worn version of the same. That's why Saturday sounds slightly less "English" than Tuesday or Wednesday — because it isn't. It's the one day that never got translated into Anglo-Saxon mythology.
Curiously, Romance languages made the opposite move. Spanish *sábado* and French *samedi* come from the Hebrew word "Sabbath" — reflecting Christian and Jewish influence on the Roman calendar's later evolution.
Why the pattern matters
Every day of the week in English is a small time capsule. Two days point to celestial bodies (Sun, Moon), four days point to Anglo-Saxon and Norse gods (Tiw, Woden, Thor, Frige), and one day points to a Roman god who didn't get translated (Saturn). The pattern quietly preserves a moment in linguistic history — when Germanic and Roman cultures met, and Germanic speakers translated most of the Roman names into their own mythology, keeping the astronomical structure but replacing the divine personnel.
You're carrying a piece of that meeting around with you every time you name a day. It's one of the older, more consistent surviving artifacts in the English language.
