a·li·en (ālē-ən, ālyən)
1. Owing political allegiance to another country or government; foreign: alien residents.
2. Belonging to, characteristic of, or constituting another and very different place, society, or person; strange.
3. Dissimilar, inconsistent, or opposed, as in nature: emotions alien to her temperament.
1. An unnaturalized foreign resident of a country. Also called noncitizen.
2. A person from another and very different family, people, or place.
3. A person who is not included in a group; an outsider.
4. A creature from outer space: science fiction about an invasion of aliens.
5. 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. a·li·ened, a·li·en·ing, a·li·ens
To transfer (property) to another; alienate.
[Middle English, from Old French, from Latin aliēnus, from alius, other; see al-1 in the Appendix of Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2019 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.