person reentering a country; reentrant
Refers to a person who reenters a country, typically used in immigration or travel contexts.
Reentrants must present their passports at immigration.
入国者 means 'person entering a country' (first entry), while 再入国者 specifically means 'person reentering a country'.
Compound of 再 (re-), 入国 (entry into a country), and 者 (person).