DictionaryalienExtraterrestrial
noun / adjective

alien

AY-lee-uhn/ˈeɪliʌn/

Foreign to a particular place, community, or familiar experience.

The towering rock formations make this landscape seem alien to the traveler.

A traveler encounters an unfamiliar landscape of unusual towering rock formations, clearly foreign surroundings.
Etymology

Latin alienus links “belonging to another” with “foreign” or “strange.” The connection is between what is not one's own and what seems unfamiliar or belongs elsewhere.

In context

Old Time Radio Researchers6:11
inside the spaceship stands the spaceman he is a man entirely like ourselves he wears a close-fitting suit like a deep-sea divers armor butt of alien material
[1954] Lux Radio Theatre - The Day the Earth Stood Still

More examples

  • The novel describes an alien arriving from another planet.
  • The form uses alien for a person without citizenship.
  • Such casual dishonesty is alien to her experience.

Forms

alien · aliens

Similar words

foreign
Usually concerns another country rather than unfamiliarity in general.
extraterrestrial
Specifically concerns beings or things originating beyond Earth.