The Collaborative International Dictionary of English v.0.48:

Emigration \Em`i*gra"tion\, n. [L. emigratio: cf. F.
   ['e]migration.]
   1. The act of emigrating; removal from one country or state
      to another, for the purpose of residence, as from Europe
      to America, or, in America, from the Atlantic States to
      the Western.
      [1913 Webster]

   2. A body emigrants; emigrants collectively; as, the German
      emigration.
      [1913 Webster]

WordNet (r) 3.0 (2006):

emigration
    n 1: migration from a place (especially migration from your
         native country in order to settle in another) [syn:
         emigration, out-migration, expatriation]