Meaning

noun the movement of persons from one country or locality to another

noun a group of people migrating together (especially in some given time period)

noun (chemistry) the nonrandom movement of an atom or radical from one place to another within a molecule

originFrom Middle French migration and its source, Latin migrātiō, from the participle stem of migrō (“to migrate”). Morphologically migrate + -ion.

Etymology from Wiktionary, CC BY-SA 3.0