horizontal
Americanadjective
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at right angles to the vertical; parallel to level ground.
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flat or level.
a horizontal position.
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being in a prone or supine position; recumbent.
His bad back has kept him horizontal for a week.
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near, on, or parallel to the horizon.
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of or relating to the horizon.
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measured or contained in a plane parallel to the horizon.
a horizontal distance.
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(of material on a printed page, pieces on a game board, etc.) extending across, from the left to the right of the viewer.
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of or relating to a position or individual of similar status.
He received a horizontal promotion to a different department, retaining his old salary and title.
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Economics. of or relating to companies, affiliates, divisions, etc., that perform the same or similar functions or produce the same or similar products.
Through horizontal mergers the company monopolized its field.
noun
adjective
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parallel to the plane of the horizon; level; flat Compare vertical
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of or relating to the horizon
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measured or contained in a plane parallel to that of the horizon
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applied uniformly or equally to all members of a group
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economics relating to identical stages of commercial activity
horizontal integration
noun
Other Word Forms
Etymology
Origin of horizontal
1545–55; < Latin horizont- (stem of horizōn ) horizon + -al 1
Explanation
The opposite of vertical, something horizontal is arranged sideways, like a person lying down. When you sleep (unless you're a horse), your body is horizontal: horizontal things are parallel to the ground or running in the same direction as the horizon. If you stack books horizontally, then they're on their side. You hear a lot about horizontal lines in geometry: If you picture a square, the top and bottom lines are horizontal lines.
Vocabulary lists containing horizontal
Expressions and Equations
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Geometry - Introductory
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The Number System
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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.
It accused tennis' governing bodies in the US, the UK and the EU of "horizontal price-fixing" their prize money, saying what the players earn "lags far behind" other athletes.
From BBC • May 27, 2026
What is collapsing is the undifferentiated middle — the horizontal tools that AI agents can replicate cheaply and at scale.
From MarketWatch • May 27, 2026
There was a logical connection in the horizontal merger, and the two companies had overlapping customers.
From Barron's • May 27, 2026
He has, also, ingeniously arranged his horizontal, vertical and diagonal vectors within a gigantic, symbolic, circular frame.
From The Wall Street Journal • May 1, 2026
Cade Hernandez drew a little horizontal triangle in the air between me, Markie, and himself.
From "100 Sideways Miles" by Andrew Smith
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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.