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a combining form meaning “outside,” “outer,” “external,” used in the formation of compound words:
Also, ex-.
Origin of exo-
< Greek, combining form of éxō outside Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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Examples from the Web for exo
Contemporary Examples
Historical Examples
  • She ran off to her typewriter, and in twelve minutes came back with the jingle, I'm glad I'm not an exo.

    Facts in Jingles Winifred Sackville Stoner
British Dictionary definitions for exo


(Austral) an informal word for excellent


combining form
external, outside, or beyond: exobiology, exothermal
Word Origin
from Greek exō outside
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
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Word Origin and History for exo


word-forming element used in scientific words (e.g. exoskeleton), from Greek exo "outside," related to ex "out of" (see ex-).

Online Etymology Dictionary, © 2010 Douglas Harper
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exo in Medicine

exo- pref.
Outside; external: exoskeleton.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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exo in Science
A prefix that means "outside" or "external," as in exoskeleton.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Slang definitions & phrases for exo



An exhibition game or match: I mean she's playing a freaking exo (1990s+)

The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D.
Copyright (C) 2007 by HarperCollins Publishers.
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