[ key-os ]
/ ˈkeɪ ɒs /
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a state of utter confusion or disorder; a total lack of organization or order.
any confused, disorderly mass: a chaos of meaningless phrases.
the infinity of space or formless matter supposed to have preceded the existence of the ordered universe.
(initial capital letter) the personification of this in any of several ancient Greek myths.
Obsolete. a chasm or abyss.
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Origin of chaos

First recorded in 1400–50; late Middle English, from Latin, Greek cháos; akin to chasm, yawn, gape

historical usage of chaos

Chaos comes via Latin chaos from Greek cháos “the first state of the universe, the formless state of primordial matter, (personified) the parent of Darkness and Night, infinite and empty space, expanse of air.” The original Greek meaning of cháos was “hole, empty space, yawning opening,” from an unrecorded cháwos and related to the adjective chaûnos “loose, spongy, having holes.”
The first meaning in English was “an immeasurable and formless void, infinite darkness,” especially in reference to the state that preceded God’s Creation of the universe. The current meaning “a state of utter confusion and disorder (resembling the primordial state)” first appeared about 1533.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use chaos in a sentence

British Dictionary definitions for chaos

/ (ˈkeɪɒs) /

complete disorder; utter confusion
(usually capital) the disordered formless matter supposed to have existed before the ordered universe
an obsolete word for abyss

Derived forms of chaos

chaotic (keɪˈɒtɪk), adjectivechaotically, adverb

Word Origin for chaos

C15: from Latin, from Greek khaos; compare chasm, yawn
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

Scientific definitions for chaos

[ kāŏs′ ]

The behavior of systems that follow deterministic laws but appear random and unpredictable. Chaotic systems very are sensitive to initial conditions; small changes in those conditions can lead to quite different outcomes. One example of chaotic behavior is the flow of air in conditions of turbulence. See more at fractal.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Cultural definitions for chaos


A new branch of science that deals with systems whose evolution depends very sensitively upon the initial conditions. Turbulent flows of fluids (such as white water in a river) and the prediction of the weather are two areas where chaos theory has been applied with some success.

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.