a combining form meaning “the earth,” used in the formation of compound words: geochemistry.

Origin of geo-

< Greek geō-, combining form of the earth

Definition for geo (2 of 2) Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for geo

British Dictionary definitions for geo (1 of 2)



/ (ˈdʒiːəʊ) /

noun plural geos or gios

(esp in Shetland) a small fjord or gully

Word Origin for geo

C18: from Old Norse gjā ravine; related to Old English gionian to yawn

British Dictionary definitions for geo (2 of 2)


combining form

indicating earthgeomorphology

Word Origin for geo-

from Greek, from earth
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

Medicine definitions for geo



The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Science definitions for geo


A prefix that means “earth,” as in geochemistry, the study of the Earth's chemistry.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.