horizontal

UK: /ˌhɒrɪˈzɒnt^əl/

US: /ˌhɔrəˈzɑntəl, ˌhɑr-/

US: (hôr′ə zon′tl, hor′-)

WordReference Random House Learner's Dictionary of American English © 2026

hor•i•zon•tal /ˌhɔrəˈzɑntəl, ˌhɑr-/   adj. 

1. parallel to level ground;
   flat or level:
   a horizontal position.

hor•i•zon•tal•ly, adv. 

WordReference Random House Unabridged Dictionary of American English © 2026

hor•i•zon•tal  (hôr′ə zon′tl, hor′-), adj. 

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 pertaining 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 pertaining 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, Business of or pertaining 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.

n. 

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

• Latin horizont- (stem of horizōn) horizon + -al¹
• 1545–55

hor•i•zon•tal•i•ty  (hôr′i zon tal′i tē, hor′-), hor′i•zon′tal•ness, n.  hor′i•zon′tal•ly, adv. 

Collins Concise English Dictionary © HarperCollins Publishers::

horizontal / ˌhɒrɪˈzɒnt^əl/ adjective

1. parallel to the plane of the horizon; level; flat
   Compare vertical1
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. relating to identical stages of commercial activity: horizontal integration

noun

1. a horizontal plane, position, line, etc

ˌhorizonˈtality, ˌhoriˈzontalness noun

ˌhoriˈzontally adverb