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a combining form meaning “alien,” “strange,” “guest,” used in the formation of compound words: xenogamy, xenolith.
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Also especially before a vowel, xen-.

Origin of xeno-

Combining form of Greek xénos stranger, guest (noun); alien, foreign, strange (adj.)
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2021


What does xeno- mean?

Xeno- is a combining form used like a prefix meaning “alien,” “strange,” or “guest.” It is used in a variety of domains, including in botany, medicine, mineralogy, the social sciences, and zoology.

Xeno- comes from the Greek xénos, a noun meaning “stranger, guest” or an adjective meaning “foreign, strange.” The name of the chemical element (and noble gas) Xenon also derives from the Greek xénos.

What are variants of xeno-?

When combined with words or word elements that begin with a vowel, xeno- becomes xen-, as in xenarthral.

Examples of xeno-

An example of a word you may have heard that features xeno- is xenophobia, “an aversion or hostility to, disdain for, or fear of foreigners, people from different cultures, or strangers.”

We know xeno- can refer to “foreigner.” And the -phobia portion of the word? That’s right, -phobia designates abnormal or irrational fears. So, xenophobia literally translates to “fear of foreigners.”

A connection to xeno- in popular culture is xenomorph, a name for the alien creature in the sci-fi horror franchise Alien. Learn more about this unusual specimen of a word in our entry for the term.

What are some words that use the combining form xeno-?

What are some other forms that xeno- may be commonly confused with?

We’d forgive you for confusing xeno- with Zeno, the name of two influential ancient Greek philosophers. But do note the name and combining form are unrelated. Xeno- is also not to be confused with the occasional combining form zeno-, used in a few words to refer to the planet Jupiter.

Break it down!

The combining form -lith means “stone.” What does xenolith literally mean?

How to use xeno- in a sentence

  • Regardless of his position as a xeno-naturalist, he is a complete layman in the psychosciences.

    Little Fuzzy|Henry Beam Piper

British Dictionary definitions for xeno-


before a vowel xen-

combining form
indicating something strange, different, or foreignxenogamy

Word Origin for xeno-

from Greek xenos strange
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

Medical definitions for xeno-


Stranger; foreigner:xenophobia.
Strange; foreign; different:xenophthalmia.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.