horizon
Americannoun
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the line or circle that forms the apparent boundary between earth and sky.
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Astronomy.
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the small circle of the celestial sphere whose plane is tangent to the earth at the position of a given observer, or the plane of such a circle sensible horizon.
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Also called rational horizon. the great circle of the celestial sphere whose plane passes through the center of the earth and is parallel to the sensible horizon of a given position, or the plane of such a circle celestial horizon.
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the limit or range of perception, knowledge, or the like.
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Usually horizons the scope of a person's interest, education, understanding, etc..
His horizons were narrow.
- Synonyms:
- viewpoint, domain, perspective, world
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Geology. a thin, distinctive stratum useful for stratigraphic correlation.
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Also called soil horizon. any of the series of distinctive layers found in a vertical cross section of any well-developed soil.
noun
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Also called: visible horizon. apparent horizon. the apparent line that divides the earth and the sky
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astronomy
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Also called: sensible horizon. the circular intersection with the celestial sphere of the plane tangential to the earth at the position of the observer
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Also called: celestial horizon. the great circle on the celestial sphere, the plane of which passes through the centre of the earth and is parallel to the sensible horizon
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the range or limit of scope, interest, knowledge, etc
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a thin layer of rock within a stratum that has a distinct composition, esp of fossils, by which the stratum may be dated
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a layer in a soil profile having particular characteristics See A horizon B horizon C horizon
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likely or about to happen or appear
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The apparent intersection of the Earth and sky as seen by an observer.
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See sensible horizon
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Geology
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A specific position in a stratigraphic column, such as the location of one or more fossils, that serves to identify the stratum with a particular period.
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A specific layer of soil or subsoil in a vertical cross-section of land.
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Archaeology A period during which the influence of a particular culture spread rapidly over a defined area.
Other Word Forms
Derived Forms
Inflected Forms
Nouns
Etymology
Origin of horizon
First recorded in 1540–50; from Latin horizōn, from Greek horízōn (kýklos) “bounding (circle),” equivalent to horíz(ein) “to bound, limit” + -ōn present participle suffix (nominative singular); replacing Middle English orizonte, from Middle French, from Latin horizontem, accusative of horizōn
Explanation
When you look out your window and note the furthest point you can see––the line where the sky meets the earth––that edge is called the horizon. Horizon can also mean the edge of something in a figurative sense. When you are thinking about your life, it can be difficult to get very far beyond where you are. Teenagers have a hard time imagining beyond the horizons of young adulthood. People expecting a baby often put much of their focus on infancy––having a child who can sit up or even walk is beyond the horizons of their thinking.
Vocabulary lists containing horizon
From Ascension to Zenith: Astronomy and Stargazing Terms
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myPerspectives 8.1
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100 SAT Words Beginning with "H"
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
Nobody can help you with a financial question unless they know your general time horizon.
From MarketWatch ● Jul. 22, 2026
Around the village is the vast Kazakh steppe, stretching seemingly endlessly into a horizon broken only by the solitary tower of a cement plant.
From Barron's ● Jul. 22, 2026
With autumn and winter on the horizon and Russia likely to launch yet another assault on Ukraine's battered energy grid, some fear that the country will be more vulnerable.
From BBC ● Jul. 17, 2026
“What it’s all about is expanding that sense of scope and horizon, the analog color, that sense of immersion.”
From Los Angeles Times ● Jul. 17, 2026
And then we were in the country, the flat Dutch farmland stretching to the horizon, ruler-straight canals sweeping past the window.
From "The Hiding Place" by Corrie ten Boom
And once dawn comes, the desert performs the same magic: long horizons, unfamiliar landscapes, the creeping feeling that we are small, short-lived creatures on an immense ancient planet.
From Los Angeles Times ● Jul. 22, 2026
Ever ambitious and eager to test new horizons, Keegan announced midway through the 1976-77 season that he would leave Liverpool at the end of the campaign.
From BBC ● Jul. 20, 2026
Inflation expectations for both one- and three-year horizons were up in a recent New York Fed survey.
From MarketWatch ● Jul. 10, 2026
Our research supports this conjecture, as we found that companies with more cheap stock experienced lower stock returns over longer horizons after going public.
From Salon ● Jun. 13, 2026
A sudden, hard wind swirled up around them, and the monster spread its arms out wide, so wide they seemed to reach to opposite horizons, so wide they seemed big enough to encompass the world.
From "A Monster Calls" by Patrick Ness
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.