Sun worship, “the day of the sun,” and “Sunday”
The Romans called the sun god “Mithra” and “Apollo,” and they especially worshiped the sun on “the first day of the week,” also called “Dies Solis” (Latin), which means, “day of the sun.” The name “Sunday” was adopted “because this day was anciently dedicated to the sun, or to its worship. The first day of the week.” Webster’s Dictionary; 1929 editio