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

During periods of substantial uncertainty such as the present, elevated perceptions of risk can also shorten the time horizon over which investors make decisions. —Jeffrey Schulze, Forbes.com, 9 June 2025

The answer will be highly personal, driven by your risk tolerance, time horizon and knowledge. —Jeanne Sahadi, CNN Money, 7 June 2025

Towards the end of the month, Mercury will be visible in the western horizon, the space agency said. —Hannah Poukish, Sacbee.com, 6 June 2025

The moon will be seen to close in on Spica throughout the night, with the duo eventually setting in close proximity on the western horizon in the pre-dawn hours of June 6. —Anthony Wood, Space.com, 5 June 2025

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