Thursday and Other Days Named After Norse Gods

The English names for the days of the week are a quiet reminder of the pre-Christian past. Four of them, Tuesday, Wednesday, Thursday and Friday, are named after Germanic gods who are closely related to the gods of Norse mythology. This post explains where the names came from, how they connect to Thor and his family, and how other languages handled the same week.

The Roman origin

The seven-day week with days named after planets developed in the Roman world during the early centuries of the first millennium. The Romans named the days after the seven classical “planets” visible to the naked eye, which were themselves linked to gods: the Sun, the Moon, Mars, Mercury, Jupiter, Venus and Saturn. In Latin these were dies Solis, dies Lunae, dies Martis, dies Mercurii, dies Iovis, dies Veneris and dies Saturni.

Romance languages still preserve many of these names. In French, Tuesday to Friday are mardi, mercredi, jeudi and vendredi, from Mars, Mercury, Jupiter (Iovis) and Venus.

How the Germanic names were formed

Germanic-speaking peoples adopted the seven-day week from the Romans, probably in the first few centuries AD. Instead of keeping the Roman gods, they substituted their own gods who seemed to match. This process is sometimes called interpretatio germanica, the reverse of the Roman habit of identifying foreign gods with their own.

The substitutions were based on perceived similarities:

• Mars, the Roman war god, was matched with Tiw (Norse Týr), a god associated with war and law. This gave Tuesday.
• Mercury, the messenger and guide of souls, was matched with Woden (Norse Odin), who also guided the dead and was associated with wisdom. This gave Wednesday.
• Jupiter, the sky god who wields thunderbolts, was matched with Thunor (Norse Thor), the thunder god. This gave Thursday.
• Venus, goddess of love, was matched with Frige (Norse Frigg), Woden’s wife. This gave Friday.

Saturday kept the Roman Saturn, while Sunday and Monday are named after the sun and moon.

Thursday: Thunor’s day

The Old English name was Þunresdæg, “Thunor’s day”. Thunor is the Old English form of the same god known in Old Norse as Þórr. Over time, Old English Þunresdæg was influenced by the Old Norse Þórsdagr, probably through contact with Scandinavian settlers in England, and developed into the Middle English Thursday. Other Germanic languages show the same pattern:

• German: Donnerstag, “Donar’s day” or “thunder day”.
• Dutch: donderdag.
• Swedish, Danish and Norwegian: torsdag.
• Icelandic historically used Þórsdagur.

The connection between Jupiter and Thor makes sense. Both were sky gods closely linked to thunder, and both were important protector figures.

Icelandic: a different path

Interestingly, Icelandic no longer uses the gods’ names. In the 1100s, Jón Ögmundarson, the bishop of Hólar, is said to have encouraged Icelanders to replace the pagan names with neutral ones. Thursday became fimmtudagur, “fifth day”. Tuesday and Wednesday became þriðjudagur (“third day”) and miðvikudagur (“mid-week day”), and Friday became föstudagur (“fasting day”). This change stuck, so modern Icelandic is unusual among Germanic languages in avoiding the old god names.

Tuesday and Týr

Tuesday comes from the Old English Tīwesdæg, named after Tiw, the god known in Norse as Týr. In Norse mythology Týr is the god who places his hand in the mouth of the wolf Fenrir as a guarantee while the gods bind it. When the wolf realises it has been tricked, it bites off his hand. Týr is often seen as an older sky god whose importance had faded by the Viking age.

Wednesday and Odin

Wednesday comes from Old English Wōdnesdæg, “Woden’s day”. Woden is the English form of Odin, Thor’s father in Norse mythology and the chief of the gods. Dutch woensdag and the Scandinavian onsdag preserve the same origin. German replaced it with Mittwoch, “mid-week”.

Friday and Frigg

Friday comes from Old English Frīgedæg, named after Frige, the Old English form of Frigg, Odin’s wife. There is some debate about whether the name refers to Frigg or to Freyja, another goddess, since the two are sometimes confused. Most linguists connect it with Frigg.

Other traces in English

Days of the week are not the only place where the old gods appear in English. Place names in England such as Thundersley in Essex and Thursley in Surrey are thought to come from Thunor. Personal names derived from Old Norse, such as Thurston (Þórsteinn), arrived with Scandinavian settlers. The word “thunder” itself is closely related to Thor’s name.

Why these names survived

It may seem surprising that names honouring pagan gods survived for more than a thousand years of Christianity. The answer is probably that, by the time Christianity arrived, the names were simply everyday vocabulary. Most people would not have thought of a god every time they named a day, in the same way modern speakers rarely think of Thor when they say Thursday. The Icelandic reform shows that changing such names took deliberate effort, which in most places never happened.

Months and festivals

The gods did not leave their names on the months in English, which come from Latin. But some festivals preserve older traditions. The word Yule, for example, comes from the Old Norse jól and Old English géol, a midwinter festival that existed before Christianity and was later merged with Christmas. In Scandinavia, Christmas is still called jul. Easter is thought by some to come from the name of an Anglo-Saxon goddess, Ēostre, mentioned by the monk Bede, though this is debated by historians.

So each Thursday quietly preserves a trace of the thunder god in everyday speech, more than a thousand years after his worship faded.