The Collaborative International Dictionary of English v.0.48:

Atlanta \At*lan"ta\, n. [NL., fr. Gr. ?.] (Zool.)
   A genus of small glassy heteropod mollusks found swimming at
   the surface in mid ocean. See Heteropod.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Atlanta
    n 1: state capital and largest city of Georgia; chief commercial
         center of the southeastern United States; was plundered and
         burned by Sherman's army during the American Civil War
         [syn: Atlanta, capital of Georgia]
    2: a siege in which Federal troops under Sherman cut off the
       railroads supplying the city and then burned it; 1864 [syn:
       Atlanta, battle of Atlanta]