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hor·i·zon·tal

(hôr′ĭ-zŏntl, hŏr′-)

adj.

1. Of, relating to, or near the horizon.

a. Parallel to or in the plane of the horizon.

b. At right angles to a vertical line.

3. Occupying or restricted to the same level in a hierarchy: a horizontal study of verbal ability; a horizontal transfer by an employee.

4. Medicine Of or relating to transmission of infection by contact with or physical proximity to an infected individual or fomite.

Something, such as a line, plane, or object, that is horizontal.

[French, from Latin horizōn, horizont-, horizon; see HORIZON.]

hor′i·zon·tali·ty (-zən-tălĭ-tē), hor′i·zontal·ness n.

hor′i·zontal·ly adv.

Indo-European & Semitic Roots Appendices

Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:

Indo-European Roots

Semitic Roots

The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.

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