Administration
****** AD Advertisement
****** AD Adult
****** AD Adapted
****** AD Anno Domini (Latin: In the Year of Our Lord; referring to the Gregorian calendar system)
****** AD Archduke
****** AD Alternate Days
****** AD Andorra (top-level domain)
****** AD Admiral
****** AD Adjoint (mathematics; group theory)
****** AD Andes
****** AD Art Director
****** AD Addendum
****** AD Active Duty
****** AD Alzheimer's Disease