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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 ��é�ԴDz�, 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 ��é�ԴDz�.

What are variants of xeno-?

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

An example of a word you may have heard that features xeno- ������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-?

• xenobiotic
• xenoblast
• xenocurrency
• xenocryst
• xenodiagnosis
• xenogamy
• xenogenesis
• xenolith
• xenomorphic
• xenoparasite

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

• xero-
• xylo-
• zeno-

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.

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