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Geo- is a combining form used like a prefix meaning “earth.” It is often used in scientific terms in a variety of fields. In some rare instances, such as the term geocode, geo- is used as an abbreviation of geographical.

Geo- comes from Greek ��ê, meaning “earth.” A synonym of ��ê is ���ٳ�ṓn, which is the source of several words related to the underworld, such as .

What are variants of geo-?

When combined with words or word elements that begin with a vowel, geo- becomes ge-, as in geanticline. Want to know more? Read our �y��vlogs That Use article for ge-.

An example of a word you have likely encountered that features geo- is geology, “the science that deals with the dynamics and physical history of the earth.”

We know geo- means “earth,” so the -logy portion of the word? That’s right, -logy refers to “study,” from the Greek ���Dz�í��. Geology literally translates to “study of the earth.”

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

• geobotany
• geocarpy
• geocline
• geocentric
• geochemistry
• geochronology
• geochronometry
• geodesic dome
• geodesic line
• geodesy (using the equivalent form of geo- in Greek)
• geodynamics
• geognosy (using the equivalent form of geo- in French)
• geographical (using the equivalent form of geo- in Greek)
• geography (using the equivalent form of geo- in Greek)
• geohydrology
• geological timescale
• geologist
• geomagnetic
• geometry (using the equivalent form of geo- in Greek)
• geomorphic
• geonavigation
• geophone
• geophysics
• geophyte
• geopolitical
• georama
• geoscience
• geoscientist
• geosphere
• geosyncline
• geotag
• geotaxis
• geotectonic
• geotherm
• geothermal
• geothermal energy
• geotropism

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

• gero-
• geront-
• geronto-

Not every word that begins with the exact letters ge-, such as or geoduck, is necessarily using the combining form ge- to denote “earth.” Learn why geoduck is the name of a kind of saltwater clam at our entry for the word.

Given the meaning of geo-, what is another name for the discipline known as geoscience?