The word "dominicus" is not commonly used in modern English, but it is derived from Latin. In English, the more familiar term is "Sunday." Here’s a simple explanation:
Dominicus (noun): Refers to the first day of the week, which is Sunday. This day is traditionally observed as a day of rest and worship by many Christians.
In summary, while "dominicus" is a historical term connected to the Latin language and Christian traditions, you will almost always use "Sunday" in everyday English.