horizon

noun

ho·​ri·​zon hə-ˈrī-zᵊn 

1

a

: the line where the earth seems to meet the sky : the apparent junction of earth and sky

sailing toward the horizon

b

: the great circle on the celestial sphere formed by the intersection of the celestial sphere with a plane tangent to the earth's surface at an observer's position see azimuth illustration

c

: range of perception or experience

broaden your horizons

d

: something that might be attained

opening up new horizons in the field of cancer research

2

a

geology : a natural soil layer deposited at a particular time usually identified by distinctive fossils

b

geology : any of the reasonably distinct layers of soil or its underlying material in a vertical section of land

c

anthropology : a cultural area or level of development indicated by separated groups of artifacts

horizonal

hə-ˈrī-zᵊn-əl 

adjective

Examples of horizon in a Sentence

We sailed toward the horizon.

The sun rose slowly over the eastern horizon.

These discoveries have opened up new horizons in the field of cancer research.

Recent Examples on the Web

Sky-gazers should look toward the western horizon during this time period, Gurdemir and Marc Hairston, an astrophysicist at the University of Texas at Dallas, said. —Miriam Fauzia, Dallas Morning News, 5 Feb. 2026

Their 20-year time horizon might just have been too conservative. —Leo Schwartz, Fortune, 4 Feb. 2026

Let that be a test of whether or not Canucks president Jim Rutherford and general manager Patrik Allvin have a sense of the depths of Vancouver’s crisis, and the sort of remedies required to resuscitate the value of the team’s hockey holdings over a multiyear horizon. —Thomas Drance, New York Times, 3 Feb. 2026

For the best odds, aim for a dark horizon away from city lights and give your eyes about 20 minutes to adjust. —Michael D'estries, Travel + Leisure, 3 Feb. 2026

Word History

Etymology

Middle English orizon, from Late Latin horizont-, horizon, from Greek horizont-, horizōn, from present participle of horizein to bound, define, from horos boundary; perhaps akin to Latin urvum curved part of a plow

First Known Use

14th century, in the meaning defined at sense 1a

Phrases Containing horizon

• A horizon
• artificial horizon
• B horizon
• C horizon
• cloud on the horizon
• event horizon
• gyro horizon
• on the horizon
• the horizon

Rhymes for horizon

• mizen

Kids Definition

horizon

noun

ho·​ri·​zon ˈhə-ˈrīz-ᵊn 

1

: the line where the earth or sea seems to meet the sky

2

: the limit or range of a person's outlook or experience

reading broadens our horizons

3

: a distinct layer of soil or its underlying material in a vertical section of land

horizonal

-ˈrīz-nəl 

-ᵊn-əl

adjective