1. (noun)foreigner, alien, noncitizen, outlander a person who comes from a foreign country; someone who does not owe allegiance to your country
2. (noun)stranger, alien, unknown anyone who does not belong in the environment in which they are found
3. (adj)extraterrestrial being, extraterrestrial, alien a form of life assumed to exist outside the Earth or its atmosphere
4. (adj)alien, foreign not contained in or deriving from the essentialnature 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"
5. (verb)alien, exotic being or from or characteristic of another place or part of the world "alien customs"; "exotic plants in a greenhouse"; "exotic cuisine"
7. (verb)estrange, alienate, alien, disaffect arouse hostility or indifference in where there had formerly been love, affection, or friendliness "She alienated her friends when she became fanatically religious"
Definitions of 'alien'
Webster 1913 Dictionary
1. (adj)alien not belonging to the same country, land, or government, or to the citizens or subjects thereof; foreign; as, alien subjects, enemies, property, shores
2. (adj)alien wholly different in nature; foreign; adverse; inconsistent (with); incongruous; -- followed by from or sometimes by to; as, principles alien from our religion
3. (noun)alien a foreigner; one owing allegiance, or belonging, to another country; a foreign-born resident of a country in which he does not possess the privileges of a citizen. Hence, a stranger. See Alienage
4. (noun)alien one excluded from certain privileges; one alienated or estranged; as, aliens from God's mercies
5. (verb)alien to alienate; to estrange; to transfer, as property or ownership
Definition of alien 
