Anno Domini (AD or A.D. ) and Before Christ (BC or B.C. ) are designations used to label or number years used with the Julian and Gregorian calendars. The term Anno Domini is Medieval Latin, translated as In the year of the Lord, and as in the year of our Lord. It is sometimes specified more fully as Anno Domini Nostri Iesu (Jesu) Christi (“In the Year of Our Lord Jesus Christ”).