Meaning

noun a person who comes from a foreign country; someone who does not owe allegiance to your country

noun anyone who does not belong in the environment in which they are found

noun a form of life assumed to exist outside the Earth or its atmosphere

originFrom Middle English alien, a borrowing from Old French alien, aliene, from Latin aliēnus (“belonging to someone else”, later “exotic, foreign”), from Latin alius (“other”), from Proto-Indo-European *h₂élyos. Related to English else.

Etymology from Wiktionary, CC BY-SA 3.0