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
sound like a broken record
to say the same thing over and over again
The boy's mother sounds like a broken record when she tells him to clean his room.