mi ‧ gra ‧ tion AC /maɪˈɡreɪʃ ə n/ BrE AmE noun [uncountable and countable]
[ Word Family: noun : ↑ migration , ↑ migrant ; verb : ↑ migrate ; adjective : ↑ migratory ]
1 . when large numbers of people go to live in another area or country, especially in order to find work
2 . when birds or animals travel regularly from one part of the world to another
3 . when people start using a different computer system, or information is moved to a different computer system