- A.D.† Catholic_Encyclopedia ► Ecclesiastical Abbreviations► Abbreviation in Catacomb InscriptionsAnte Diem (e.g. in the phrase, "Ante Diem VI [or Sextum] Kal. Apriles", is equivalent to the sixth day before the Calends of April, counting both the Calends and the day intended to be indicated); or Anima Dulcis ("Sweet Soul")► Abbreviation in general use, chiefly EcclesiasticalAnno Domini ("Year of Our Lord")
The Catholic Encyclopedia, Volume VIII. — New York: Robert Appleton Company. Nihil Obstat. 1910.