Source : Webster's Revised Unabridged Dictionary (1913)

Immigration \Im"mi*gra"tion\, n. [Cf. F. immigration.]
   The act of immigrating; the passing or coming into a country
   for the purpose of permanent residence.

         The immigrations of the Arabians into Europe. --T.
                                                  Warton.

Source : WordNet®

immigration
     n 1: migration into a place (especially migration to a country of
          which you are not a native in order to settle there)
          [syn: {in-migration}]
     2: the body of immigrants arriving during a specified interval;
        "the increased immigration strengthened the colony"