[ ey-lee-uhn, eyl-yuhn ]
/ ˈeɪ li ən, ˈeɪl yən /
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See synonyms for: alien / aliens on Thesaurus.com



11 nonnative, exotic, nonindigenous, imported, introduced, transplanted.


Are "Immigrant," "Ex-pat," And "Alien" Synonyms?

The words "immigrant," "expat," and "alien" all have some history and tensions behind them. Is one word better to use than the others? This man helps us figure it out.

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Origin of alien

First recorded in 1300–50; Middle English, from Middle French, from Latin aliēnus “belonging to or affecting someone else; someone else's; not one's own; foreign,” equivalent to ali(us) “other” + -ēnus adjective suffix

usage note for alien

historical usage of alien


non·al·ien, noun, adjectivepro·al·ien, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023


What does alien mean?

Historically, the word alien has been used in a way that is now often considered disparaging and offensive: to refer to a person who was born in one country and now lives in another country without having become a citizen.

Alien and its more general synonym foreigner are now often considered disparaging and offensive due to being used in a way that’s intended to otherize a person—mark them as different and unwelcome. Such use is typically attributed to xenophobia, racism, and anti-immigrant stances.

This sense of alien is found in legal terms like ​​resident alien and illegal alien. General and legal use of these terms has decreased in recent years, but they are still in use in many cases.

Relatedly, many object to the word illegal in illegal alien and illegal immigrant due to its implication that a person’s very existence can be illegal.

There are other common uses of the word alien that are not considered offensive, but that are also based on the idea of something being unfamiliar or from an entirely different place.

Alien can be used as an adjective to describe something as entirely unfamiliar, as in It was the first time he had returned in many years, and the place now seemed alien to him. The word foreign can be used in the same way.

The word alien is also commonly used as a noun to refer to a being from another planet, sometimes called an extraterrestrial or a space alien. The classic image of an alien from science fiction and pop culture (the one that comes out of a flying saucer) is a little green humanoid with a big head and large eyes. But aliens have been depicted in many different ways.

Where does alien come from?

The first records of the word alien come from around 1300. It ultimately comes from the Latin word aliēnus, meaning “foreign,” which itself comes from the word alius, meaning  “other.”

Related words include the verb alienate, meaning “to cause to be withdrawn or isolated,” as well as the adjective form alienated and the noun alienation.

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How is alien used in real life?

When used in the context of citizenship and immigration, the word alien is often considered disparaging and offensive. However, it’s also commonly used as an adjective meaning “unfamiliar” and to refer to a being from another planet, especially in the context of science fiction.





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True or False? 

The word alien derives from a Latin word meaning “other.”

How to use alien in a sentence

British Dictionary definitions for alien

/ (ˈeɪljən, ˈeɪlɪən) /

(tr) rare to transfer (property, etc) to another

Derived forms of alien

alienage (ˈeɪljənɪdʒ, ˈeɪlɪə-), noun

Word Origin for alien

C14: from Latin aliēnus foreign, from alius other
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for alien

[ ālē-ən ]

Introduced to a region deliberately or accidentally by humans. Starlings, German cockroaches, and dandelions are species that are alien to North America but have become widely naturalized in the continent. Compare endemic indigenous.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.