Why is Sunday called “Chủ Nhật” in Vietnamese?

Vietnamese names most weekdays by number: Thứ Hai (Monday, “second day”), Thứ Ba (Tuesday, “third”), Thứ Tư (Wednesday, “fourth”), all the way to Thứ Bảy (Saturday, “seventh”). Sunday breaks the pattern: it’s Chủ Nhật, literally “Lord’s Day.” The term entered Vietnamese through Portuguese Catholic missionaries in the 17th century, who arrived alongside the Quốc ngữ romanized writing system. The Christian frame stuck even though most Vietnamese aren’t Catholic. Modern Vietnamese keeps the religious origin word despite the country’s mostly Buddhist and folk-religious population.

In this clip, a vlogger walks through quiet city streets: “Hôm nay là Chủ Nhật... không có ai cả vào Chủ Nhật, đặc biệt là vào buổi sáng” (“today is Sunday... no one is around on Sunday, especially in the morning”).