Various forms of Latin day names are used in many countries that use Latin-based languages.

This list also includes the Greek-day names.

You may think that Portuguese should be listed here because it’s a Latin-based language, but Portugal dropped the five planetary names for the days of the week and replaced them with numerical references because it adopted the regular ecclesiastical (Roman-Catholic) system, which was once numerical, in an effort to eliminate the use of the names of the Roman “pagan” gods and goddesses. It’s interesting to note that names for Greek days follow the same pattern (as shown below).