Yes aliens exist,
a·li·en ( P ) Pronunciation Key (l-n, lyn)
adj.
Owing political allegiance to another country or government; foreign: alien residents.
Belonging to, characteristic of, or constituting another and very different place, society, or person; strange. See Synonyms at foreign.
Dissimilar, inconsistent, or opposed, as in nature: emotions alien to her temperament.
n.
An unnaturalized foreign resident of a country. Also called noncitizen.
A person from another and very different family, people, or place.
A person who is not included in a group; an outsider.
A creature from outer space: science fiction about an invasion of aliens.
Ecology. An organism, especially a plant or animal, that occurs in or is naturalized in a region to which it is not native.
tr.v. Law a·li·ened, a·li·en·ing, a·li·ens
To transfer (property) to another; alienate.
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[Middle English, from Old French, from Latin alinus, from alius, other. See al-1 in Indo-European Roots.]
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Source: The American Heritage® Dictionary of the English Language, Fourth Edition
Copyright © 2000 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
Alien
Any person who is not a citizen of the country in which he or she lives.
Investopedia Commentary
Aliens are not given the same rights as the citizens of the country in which they live.
See also: Economic Refugee, Non-Resident Alien, Resident Alien
Source: Investopedia.com. Copyright © 1999-2005 - All rights reserved. Owned and Operated by Investopedia Inc.
Main Entry: 1alien
Pronunciation: 'A-lE-&n, 'Al-y&n
Function: adjective
Etymology: Latin alienus not one's own, foreign
: relating, belonging, or owing allegiance to another country or government
Source: Merriam-Webster's Dictionary of Law, © 1996 Merriam-Webster, Inc.
Main Entry: 2alien
Function: noun
: a foreign-born resident who has not been naturalized and is still a subject or citizen of a foreign country
Source: Merriam-Webster's Dictionary of Law, © 1996 Merriam-Webster, Inc.
Main Entry: 3alien
Function: transitive verb
: ALIENATE
Source: Merriam-Webster's Dictionary of Law, © 1996 Merriam-Webster, Inc.
alien
adj 1: not 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" [syn: foreign] 2: being or from or characteristic of another place or part of the world; "alien customs"; "exotic plants in a greenhouse"; "exotic cuisine" [syn: exotic] n 1: a person who comes from a foreign country; someone who does not owe allegiance to your country [syn: foreigner, noncitizen, outlander] [ant: citizen] 2: anyone who does not belong in the environment in which they are found [syn: stranger, unknown] 3: a form of life assumed to exist outside the Earth or its atmosphere [syn: extraterrestrial being, extraterrestrial] v 1: transfer property or ownership; "The will aliened the property to the heirs" [syn: alienate] 2: arouse hostility or indifference in where there had formerly been love, affection, or friendliness [syn: estrange, alienate, disaffect]
Source: WordNet ® 2.0, © 2003 Princeton University
alien
a foreigner, or person born in another country, and therefore not entitled to
the rights and privileges of the country where he resides. Among the Hebrews
there were two classes of aliens. (1.) Those who were strangers generally, and
who owned no landed property.
(2.) Strangers dwelling in another country
without being naturalized (Lev. 22:10; Ps. 39:12). Both of these classes were
to enjoy, under certain conditions, the same rights as other citizens (Lev.
19:33, 34; Deut. 10:19). They might be naturalized and permitted to enter into
the congregation of the Lord by submitting to circumcision and abandoning
idolatry (Deut. 23:3-8). This term is used (Eph. 2:12) to denote persons who
have no interest in Christ.
Now if you mean extra-terrarestials, the odds of intelegent life being in our universe are slim to none.