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a combining form meaning “world,” “universe,” used in the formation of compound words: cosmography; in contemporary usage, sometimes representing Russian kosmo-, it may mean “outer space,” “space travel,” or “cosmic ray”: cosmonaut.
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Which form is used to state an obligation or duty someone has?
Also especially before a vowel, cosm-.
Compare astro-.

Origin of cosmo-

From Greek kosmo-, combining form of kósmos “order, good order, government, world order, the universe”; see origin at cosmos
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2022


What does cosmo- mean?

Cosmo- is a combining form used like a prefix meaning “world” or “universe.” In some cases, it represents “outer space.”

Cosmo- comes from the Greek kósmos, variously meaning “order, good order, government, world order, the universe.” The Greek kósmos is ultimately the source of the English words cosmos, cosmic, cosmopolitan, and cosmetics, among others. What does makeup have to do with the universe? Find out at our entry for the word.

What are variants of cosmo-?

When combined with words or word elements that begin with a vowel, cosmo- becomes cosm-, as in cosmism.

When used as the final element of a compound word, cosmo- becomes -cosm, as is microcosm.

Examples of cosmo-

A word you may be familiar with that features cosmo- is cosmology, a branch of philosophy and astronomy that deals with the origin and structure of the universe. Some serious out-of-this-world stuff.

As we’ve seen, cosmo- means “universe.” The second part, -logy, comes from the Greek lógos, meaning “word” and widely used in English to indicate an area of study. Cosmology, then, literally translates to “the study of the universe.”

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

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

Similar to cosmo- is the combining form astro- (think astronaut). Learn more in our Words That Use astro- article.

Break it down!

The combining form -gony means “production, genesis, origination.” What is cosmogony a theory or story of?

How to use cosmo- in a sentence

British Dictionary definitions for cosmo-


before a vowel cosm-

combining form
indicating the world or universecosmology; cosmonaut; cosmography

Word Origin for cosmo-

from Greek: cosmos
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