from The American Heritage® Dictionary of the English Language, 4th Edition

  • adj. Of, relating to, or near the horizon.
  • adj. Parallel to or in the plane of the horizon.
  • adj. At right angles to a vertical line.
  • adj. Occupying or restricted to the same level in a hierarchy: a horizontal study of verbal ability; a horizontal transfer by an employee.
  • n. Something, such as a line, plane, or object, that is horizontal.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • adj. perpendicular to the vertical; parallel to the plane of the horizon; level, flat.
  • adj. Pertaining to the horizon.
  • n. A horizontal component of a structure.

from the GNU version of the Collaborative International Dictionary of English

  • adj. Pertaining to, or near, the horizon.
  • adj. Parallel to the horizon; on a level.
  • adj. Measured or contained in a plane of the horizon.

from The Century Dictionary and Cyclopedia

  • Of or pertaining to the horizon.
  • Parallel to the horizon; at right angles to the direction of gravity at any station; being on a level; not vertical nor inclined: as, a horizontal line or surface; a horizontal position.
  • Measured or contained in a plane of the horizon: as, horizontal distance.
  • In figured bass, a dash under a note indicating that the tones of the last figured chord are to be continued without regard to the tone of the bass.
  • n. In craniometry, the line drawn from the lower edge of the orbital cavity to the middle of the ear-cavity.
  • n. Anodopetalum biglandulosum, a Tasmanian plant of the family Cunoniaceæ, which sometimes forms a tree 60–70 feet high, with a trunk 4 feet in circumference.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • adj. parallel to or in the plane of the horizon or a base line
  • n. something that is oriented horizontally


French, from Latin horizōn, horizont-, horizon; see horizon.
(American Heritage® Dictionary of the English Language, Fourth Edition)



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