The Collaborative International Dictionary of English v.0.48:
Anno Domini \An"no Dom"i*ni\ [L., in the year of [our] Lord [Jesus Christ]; usually abbrev. a. d.] In the year of the Christian era; as, a. d. 1887. [1913 Webster]WordNet (r) 3.0 (2006):
anno Domini adv 1: in the Christian era; used before dates after the supposed year Christ was born; "in AD 200" [syn: AD, A.D., anno Domini]