[ huh-rahy-zuhn ]
/ həˈraɪ zən /
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See synonyms for: horizon / horizons on Thesaurus.com

Definition of horizon

the line or circle that forms the apparent boundary between earth and sky.
  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 ).
the limit or range of perception, knowledge, or the like.
Usually ho·ri·zons . the scope of a person's interest, education, understanding, etc.: His horizons were narrow.
Geology. a thin, distinctive stratum useful for stratigraphic correlation.
Also called soil ho·ri·zon . any of the series of distinctive layers found in a vertical cross section of any well-developed soil.
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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
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2022

How to use horizon in a sentence

British Dictionary definitions for horizon

/ (həˈraɪzən) /

Also called: visible horizon, apparent horizon the apparent line that divides the earth and the sky
  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
the range or limit of scope, interest, knowledge, etc
a thin layer of rock within a stratum that has a distinct composition, esp of fossils, by which the stratum may be dated
a layer in a soil profile having particular characteristicsSee A horizon, B horizon, C horizon
on the horizon likely or about to happen or appear

Derived forms of horizon

horizonless, adjective

Word Origin for horizon

C14: from Latin, from Greek horizōn kuklos limiting circle, from horizein to limit, from horos limit
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 horizon

[ hə-rīzən ]

  1. The apparent intersection of the Earth and sky as seen by an observer. Also called apparent horizon
  2. See celestial horizon.
  3. See sensible horizon.
  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.
Archaeology A period during which the influence of a particular culture spread rapidly over a defined area.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Other Idioms and Phrases with horizon


see on the horizon.

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.