the process or act of migrating.

a migratory movement

preparations for the migration.

a number or body of persons or animals migrating together.

Chemistry . a movement or change of position of atoms within a molecule.

Physics . diffusion ( def. 3a ) .

noun

exodus , immigration , transmigration , diaspora , flight , hegira , journey , move , movement , passage , shift , transfer , trek

adjective

migratory , moving , nomadic , roving , transient , unsettled , vagrant , wandering