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
