- the distant line where the sky appears to meet the surface of the earth
- a similar line observed from the surface of the moon, etc.
- [usually pl.] the limit or extent of one's outlook, experience, interest, knowledge, etc.: travel broadens one's horizons
- Archaeol. an archaeological level or an area of culture as indicated by surviving artifacts
- Astron. the great circle on the celestial sphere perpendicular to the line from the observer's zenith to the nadir
- Geol. a layer of soil or rock identified by physical characteristics, particular fossils, etc.
Origin of horizonaltered (after L) from Middle English orizont from Old French orizonte from Classical Latin horizon from Classical Greek horiz?n (kyklos), the bounding (circle), horizon from present participle of horizein, to bound, limit from horos, boundary, limit, akin to Classical Latin urvus, city boundary, origin, originally , furrow around city
on the horizon