• synonyms

celestial horizon

noun Astronomy.
  1. See under horizon(def 2b).
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Origin of celestial horizon

First recorded in 1895–1900


  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.
  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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Origin of horizon

1540–50; < Latin horizōn < Greek horízōn (kýklos) bounding (circle), equivalent to horíz(ein) to bound, limit + -ōn present participle suffix (nominative singular); replacing Middle English orizonte < Middle French < Latin horizontem, accusative of horizōn

Synonyms for horizon

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for celestial horizon

celestial horizon

  1. See horizon (def. 2b)
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  1. Also called: visible horizon, apparent horizon the apparent line that divides the earth and the sky
  2. astronomy
    1. Also called: sensible horizonthe circular intersection with the celestial sphere of the plane tangential to the earth at the position of the observer
    2. Also called: celestial horizonthe 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 characteristicsSee A horizon, B horizon, C horizon
  6. on the horizon likely or about to happen or appear
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Derived Formshorizonless, 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

Word Origin and History for celestial horizon



late 14c., orisoun, from Old French orizon (14c., Modern French horizon), earlier orizonte (13c.), from Latin horizontem (nominative horizon), from Greek horizon kyklos "bounding circle," from horizein "bound, limit, divide, separate," from horos "boundary." The h- was restored 17c. in imitation of Latin.

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Online Etymology Dictionary, © 2010 Douglas Harper

celestial horizon in Science

celestial horizon

  1. A great circle on the celestial sphere having a plane that passes through the center of the Earth at a right angle to the line formed by an observer's zenith and nadir. The celestial horizon divides the celestial sphere into two equal hemispheres based on the observer's location, with one hemisphere representing the half of the sky visible to the observer at that location and the other representing the half that is hidden from the observer below the Earth's horizon. The celestial horizon is used as the reference point in determining a celestial body's altitude. Also called rational horizon Compare sensible horizon.
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    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. 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.
  2. Archaeology A period during which the influence of a particular culture spread rapidly over a defined area.
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The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Idioms and Phrases with celestial horizon


see on the horizon.

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