Nouns

(n)foreigner, alien, noncitizen, outlandera person who comes from a foreign country; someone who does not owe allegiance to your country
(n)stranger, alien, unknownanyone who does not belong in the environment in which they are found
(n)extraterrestrial being, extraterrestrial, aliena form of life assumed to exist outside the Earth or its atmosphere

Verbs

(v)alien, alienatetransfer property or ownership“The will aliened the property to the heirs”

Adjectives

(s)alien, foreignnot contained in or deriving from the essential nature of something“an economic theory alien to the spirit of capitalism”, “the mysticism so foreign to the French mind and temper”, “jealousy is foreign to her nature”
(s)alien, exoticbeing or from or characteristic of another place or part of the world“alien customs”, “exotic plants in a greenhouse”, “exotic cuisine”