horizon

American  

[huh-rahy-zuhn] / həˈraɪ zən /

noun

1. the line or circle that forms the apparent boundary between earth and sky.

2. Astronomy.

   1. 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.

   2. 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.

3. the limit or range of perception, knowledge, or the like.

4. Usually horizons the scope of a person's interest, education, understanding, etc..

   His horizons were narrow.

   Synonyms:

   viewpoint, domain, perspective, world

5. Geology. a thin, distinctive stratum useful for stratigraphic correlation.

6. Also called soil horizon.  any of the series of distinctive layers found in a vertical cross section of any well-developed soil.

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horizon British  

/ həˈraɪzən /

noun

1. Also called: visible horizon.   apparent horizon.  the apparent line that divides the earth and the sky

2. astronomy

   1. Also called: sensible horizon.  the circular intersection with the celestial sphere of the plane tangential to the earth at the position of the observer

   2. 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

3. the range or limit of scope, interest, knowledge, etc

4. a thin layer of rock within a stratum that has a distinct composition, esp of fossils, by which the stratum may be dated

5. a layer in a soil profile having particular characteristics See A horizon B horizon C horizon

6. likely or about to happen or appear

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horizon Scientific  

/ hə-rī′zən /

1. 1. The apparent intersection of the Earth and sky as seen by an observer.

   2. See celestial horizon

   3. See sensible horizon

2. Geology

   1. 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.

   2. A specific layer of soil or subsoil in a vertical cross-section of land.

3. Archaeology A period during which the influence of a particular culture spread rapidly over a defined area.

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horizon Idioms  

1. see on the horizon.

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Other Word Forms

• horizonless adjective

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

Example Sentences

Further out on the horizon, some elevator manufacturers are exploring the possibility of reshaping cities with magnetic-levitation, or maglev, technology, which uses powerful magnetic fields to lift and propel vehicles without physical contact.

From The Wall Street Journal • Apr. 2, 2026

Intel investors have been reacting positively to its recent announcement of a change to a joint-venture arrangement — and another a similar catalyst may be on the horizon.

From MarketWatch • Apr. 2, 2026

Although Sony Pictures Television is still pitching the series to networks and streamers, industry insiders predict that, with Dern and McKay on board, a green light is on the horizon.

From Los Angeles Times • Mar. 30, 2026

On the evening of 1 April the moon will rise low on the horizon and is far more likely to look orange than pink.

From BBC • Mar. 29, 2026

A fiery orange glow spread above the horizon.

From "Fallout: Spies, Superbombs, and the Ultimate Cold War Showdown" by Steve Sheinkin

Related Words

• boundary
• perspective
• prospect
• scope