Although the term AD still refers to the years in history prior to the birth of Jesus Christ, it now stands for Anno Domini, a Latin phrase that means "Year of our Lord" and was used by Europeans, Romans, and Latin Americans. You can be unsure about whether to use BC or AD as the correct phrase. Ad full form Additionally, it depends on the publications and historical events you are referring to. In order to properly reflect the years before the birth of Jesus Christ, the majority of contemporary literature and history books use BC, which is the full form of Before Christ.