IOM Definition of "Migrant"
An umbrella term, not defined under international law, reflecting the common lay understanding of a person who moves away from his or her place of usual residence, whether within a country or across an international border, temporarily or permanently, and for a variety of reasons. The term includes a number of well-defined legal categories of people, such as migrant workers; persons whose particular types of movements are legally-defined, such as smuggled migrants; as well as those whose status or means of movement are not specifically defined under international law, such as international students.
Note: At the international level, no universally accepted definition for “migrant” exists. The present definition was developed by IOM for its own purposes and it is not meant to imply or create any new legal category.
International Organization for Migration, Glossary on migration, IML Series No. 34, 2019, available here.