Why Saturday is named after Saturn

Updated October 19, 2026 · 5 min read

Saturday is called Saturday because it is Saturn's day: the word comes from Old English Sæterndæg, a borrowing of Latin Saturni dies, the name the Roman planetary week gave to the day ruled by the planet Saturn. It is the only English weekday that kept the name of a Roman god; the others took Germanic gods or the Sun and Moon. French, by contrast, says samedi, which comes from the Jewish Sabbath.

The planetary week

The seven-day week combines two traditions. One is Jewish: a seven-day cycle anchored by the Sabbath. The other is astrological: Greek astronomers in Hellenistic Egypt ranked the seven moving lights visible to the naked eye (the Moon, Mercury, Venus, the Sun, Mars, Jupiter and Saturn) by their apparent speed and assigned each one to rule the hours.

Cassius Dio, writing in the third century AD, explains the mechanism (Roman History 37.18–19). Rank the planets from slowest to fastest: Saturn, Jupiter, Mars, Sun, Venus, Mercury, Moon. Give the first hour of the first day to Saturn, the second to Jupiter, and so on in a loop. Because a day has 24 hours, the ruler of the first hour of the next day lands three places further along: after Saturn comes the Sun, then the Moon, Mars, Mercury, Jupiter and Venus. That is exactly the order of our weekdays.

In this astrological scheme, Saturn's day opens the series because Saturn is the slowest and most distant planet known to the ancients (see Saturn's orbit and year). In Jewish and Christian tradition, by contrast, Saturday is the seventh and last day. The planetary week was widespread in Rome by the first century AD: graffiti from Pompeii, written before the eruption of 79, already list the days by their gods.

Saturn and the Sabbath

Saturn's day coincided with the Sabbath, and Romans noticed. The Augustan poet Tibullus mentions "Saturn's sacred day" as a bad omen for setting out on a journey (Elegies 1.3). Tacitus, more hostile, suggests that the seventh-day rest might honor Saturn, the highest of the planets (Histories 5.4). The link between Saturn and the Jewish people persisted in ancient and medieval astrology.

Why French says "samedi"

When the Empire became Christian, the Church tried to erase the pagan day names. It succeeded with Sunday, dies dominicus, "the Lord's day", which displaced the day of the Sun in the Romance languages, after Constantine made the Sun's day a day of rest in 321. For Saturday, the name of the Sabbath was adopted.

The French word comes from Vulgar Latin sambati dies, where sambatum is a nasalized form of sabbatum, borrowed from Greek and probably spread by Greek-speaking Jewish and Christian communities. Sambati dies became samedi, just as Lunae dies became lundi. German Samstag has the same origin. Other Romance languages stayed closer to the classical form: Italian sabato, Spanish and Portuguese sábado, Romanian sâmbătă. So in French only Monday through Friday keep planetary names.

Why English says "Saturday"

The Germanic peoples adopted the Roman week but replaced most Latin gods with their own: Mars became Tiw, Mercury Woden, Jupiter Thor, Venus Frigg. Saturn had no obvious counterpart, so the Anglo-Saxons simply borrowed the Latin word, giving Old English Sæterndæg, later Saturday. Dutch zaterdag and Low German Saterdag did the same. The Scandinavian languages chose a different name: Danish and Norwegian lørdag, Swedish lördag, from Old Norse laugardagr, "bathing day".

The Celtic languages, closer to Rome, kept the god: Welsh dydd Sadwrn, Breton disadorn, Irish Dé Sathairn.

Saturday around the world

The planetary week traveled with astrology to India and East Asia. In Hindi, Saturday is shanivar, the day of Shani, the planet Saturn. In Japanese, doyōbi means "earth day", because Saturn is dosei, "the earth star", following the old Chinese pairing of the five visible planets with the five elements. Thai also names Saturday after Saturn. Modern Chinese, by contrast, simply numbers the days.

Hebrew shabbat and Arabic as-sabt keep the name of the day of rest. Around a single day, then, the world splits between two inheritances: the slowest planet and the day of rest.

The Saturn of the weekdays is the astrologers' Saturn, distant and slow, who fed the tradition of saturnine melancholy and of astrology. For the origin of the planet's own name, see Saturn's name and symbol; for the god himself, Saturn, the Roman god.

Sources

• Cassius Dio, Roman History 37.18–19
• Tibullus, Elegies 1.3; Tacitus, Histories 5.4
• Online Etymology Dictionary, "Saturday"
• Eviatar Zerubavel, The Seven Day Circle: The History and Meaning of the Week, New York, Free Press, 1985