horizontal

American  

[hawr-uh-zon-tl, hor-] / ˌhɔr əˈzɒn tl, ˌhɒr- /

adjective

1. at right angles to the vertical; parallel to level ground.

2. flat or level.

   a horizontal position.

3. being in a prone or supine position; recumbent.

   His bad back has kept him horizontal for a week.

4. near, on, or parallel to the horizon.

5. of or relating to the horizon.

6. measured or contained in a plane parallel to the horizon.

   a horizontal distance.

7. (of material on a printed page, pieces on a game board, etc.) extending across, from the left to the right of the viewer.

8. 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.

9. 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

• horizontals
  plural

1. anything horizontal, as a plane, direction, or object.

horizontal British  

/ ˌhɒrɪˈzɒntəl /

adjective

1. parallel to the plane of the horizon; level; flat Compare vertical

2. of or relating to the horizon

3. measured or contained in a plane parallel to that of the horizon

4. applied uniformly or equally to all members of a group

5. economics relating to identical stages of commercial activity

   horizontal integration

---

noun

1. a horizontal plane, position, line, etc

Other Word Forms

Derived Forms

• horizontality
  noun
• horizontalness
  noun
• subhorizontalness
  noun
• subhorizontal
  adjective
• unhorizontal
  adjective
• horizontally
  adverb
• subhorizontally
  adverb
• unhorizontally
  adverb

Inflected Forms

Nouns

• horizontals
  plural

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.

Example Sentences

See Examples For:

horizontal horizontals

This uneven heating created a temperature difference across the Moon's molten interior, setting off large-scale horizontal circulation.

From Science Daily ● Oct. 14, 2026

Delta Air Lines Flight 7 was taxiing for departure when its left wing clipped Air Canada Flight 785’s horizontal stabilizer at around 10:30 a.m.

From Los Angeles Times ● Oct. 6, 2026

An infield painted black sought to focus attention on the illuminated live events, while the horizontal jumps were decided in a bright pink sandpit.

From BBC ● Sep. 14, 2026

Note: WSJ interpretation that shows a 2D horizontal cross-section of OpenAI’s 3D simulation.

From The Wall Street Journal ● Sep. 8, 2026

‘Declination’ here means variation east and west, while ‘inclination’ means variation up or down from the horizontal.

From "The Invention of Science" by David Wootton

“Florida Painting” etches red horizontals into a yellow expanse flanked by vivid green, while the two-panel “Space Age Relaxation” carves white lines and colored bars into brown fields.

From Washington Post ● Nov. 3, 2021

For the Academy, City Hall’s arresting vertical lines were tranquilized into calming horizontals.

From New York Times ● Apr. 4, 2020

The only strict horizontals and verticals that will be found are in the rectangular paintings' edges.

From Los Angeles Times ● Oct. 6, 2015

"There are several decades of a growing knowledge base for horizontals," said Veers.

From Scientific American ● Aug. 18, 2011

She pointed to the dense thorny branches of a Blood Rose, cut and pinioned into cruel horizontals against the wall, yet still wild and heavy with dark red blooms.

From "How I Live Now" by Meg Rosoff