n.
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
Idiom of the Day
push one's luck
to expect to continue to escape bad luck or a negative situation
The woman was pushing her luck to continue to bother her neighbors with her loud music. Someone was going to complain someday.