不ふ法ほう入にゅう国こく

Meanings

1

noun

Refers to entering a country without legal permission; used in legal, news, and formal contexts.

country

密みつ入にゅう国こく
密入国 emphasizes sneaking in secretly, while 不法入国 is a broader legal term for any unauthorized entry.
不ふ法ほう滞たい在ざい
不法滞在 means illegal stay (overstaying a visa), whereas 不法入国 is the act of entering illegally.

Compound of 不法 (illegal) + 入国 (entry into a country).