definition of
A.D.

[1] #1 aide n. an officer who acts as military assistant to a more senior officer. wn

[2] #2 aide n. someone who acts as assistant. wn

[3] #3 A.D. r. in the Christian era; used before dates after the supposed year Christ was born; "in AD 200". wn

[4] #4 AIDS n. a serious (often fatal) disease of the immune system transmitted through blood products especially by sexual contact or contaminated needles. wn

[5] #5 ARDA n. an agency of the Intelligence Community that conducts advanced research and development related to information technology. wn