WordWeb Online

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

Derived forms: migrations

Type of: event, motion, move, movement, people, periodic event, recurrent event

Encyclopedia: Migration