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
Derived 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.
Horizontal software companies don’t serve a particular industry.
From The Wall Street Journal • Apr. 26, 2026
Horizontal gene transfer occurs when a gene moves from one species to another.
From Science Daily • Oct. 28, 2025
But the effect happens in the opposite direction: Horizontal stripes make people look narrower.
From Slate • Jun. 3, 2025
Horizontal bands of silver and gold march in a rhythmic pattern down the right side of the goddess’ face, ornament that may represent the elaborate body tattoos popular among Thracians.
From Los Angeles Times • Feb. 11, 2025
Horizontal half-moons jumped from one word over others to get to another word.
From "P.S. Be Eleven" by Rita Williams-Garcia
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.
