The influence of the weeks of Chaldaeans, Christians, and Jews slowly made itself felt in the Roman Empire, and elements of the systems were probably merged. The planetary week was at first preeminent, and the use of planetary names, based on names of pagan deities, continued even after Constantine (c.321) made the Christian week, beginning on Sunday, official in the civil calendar. The Roman names for the days of the week pervaded Western Europe; in most languages the forms are translations from Latin or attempts to assign corresponding names of divinities. The Latin names, their translations, the English equivalents, and their derivations follow: dies solis [sun's day], Sunday; dies lunae [moon's day], Monday [moonday]; dies Martis [Mars' day], Tuesday [Tiw's day]; dies Mercurii [Mercury's day], Wednesday [Woden's day]; dies Jovis [Jove's or Jupiter's day], Thursday [Thor's day]; dies Veneris [Venus' day], Friday [Frigg's day]; and dies Saturni [Saturn's day], Saturday.

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