AD /ˈeˈdi/ 縮寫
  Anno Domini, 公元
  ad /æd/ 名詞 縮寫
  advertisement, 廣告
  ad
       n : a public promotion of some product or service [syn: advertisement,
            advertizement, advertising, advertizing, advert]
       adv : in the Christian era; used before dates after the supposed
             year Christ was born; "in AD 200" [syn: A.D., anno
             Domini]
  A.D.
       adv : in the Christian era; used before dates after the supposed
             year Christ was born; "in AD 200" [syn: AD, anno
             Domini]