migration migration /maɪˈgreɪʃən/

noun

1. () The movement of persons from one country or locality to another  ( migration )
   the movement of persons from one country or locality to another
   
2. The periodic passage of groups of animals (especially birds or fishes) from one region to another for feeding or breeding  ( migration )
   the periodic passage of groups of animals (especially birds or fishes) from one region to another for feeding or breeding
   
3. (chemistry) the nonrandom movement of an atom or radical from one place to another within a molecule  ( migration )
   (chemistry) the nonrandom movement of an atom or radical from one place to another within a molecule
   
4. A group of people migrating together (especially in some given time period)  ( migration )
   a group of people migrating together (especially in some given time period)
    The migration of people in the 1800s shaped the demographics of the country.
   The migration of people in the 1800s shaped the demographics of the country.