1. belonging or relating to another person, place, or thing strange
an alien environment
2. relating, belonging, or owing allegiance to another country or government foreign
alien residents
3. exotic sense 1
alien plants
4. coming from another world extraterrestrial
alien beings an alien spaceship When it comes to knowing what alien life forms might be like, we don't have any idea.
— Kate Shuster
5. differing in nature or character typically to the point of incompatibility
ideas alien to democracy
6. a person of another family, race, or nation
aliens seeking asylum in the U.S.
7. a foreign-born resident who has not been naturalized and is still a subject or citizen of a foreign country broadly a foreign-born citizen
8. extraterrestrial
a movie about an invasion of Earth by monstrous aliens
9. exotic sense 1
Russian thistle, kudzu, and other aliens
10. alienate, estrange
11. to transfer the title of (property)
12. not familiar or like other things you have known different from what you are used to
13. from another country
14. too different from something to be acceptable or suitable
15. a person who was born in a different country and is not a citizen of the country in which he or she now lives
16. a creature that comes from somewhere other than the planet Earth
17. different from what is familiar
Keeping their hands clean was an alien idea to the young boys.
18. from another country and not a citizen of the country of residence foreign
an alien resident
19. from somewhere other than the planet earth
an alien spaceship
20. a resident who was born elsewhere and is not a citizen of the country in which he or she now lives
21. a being that comes from somewhere other than the planet earth
22. relating, belonging, or owing allegiance to another country or government
23. a foreign-born resident who has not been naturalized and is still a subject or citizen of a foreign country
illegal aliens an alien lawfully admitted to the United States for permanent residence
— U.S. Code
24. alienate