Definition of horizon:

• the great circle on the celestial sphere whose plane passes through the sensible horizon and the center of the Earth
• a specific layer or stratum of soil or subsoil in a vertical cross section of land
• the range of interest or activity that can be anticipated; " It is beyond the horizon of present knowledge"
• A plane passing through the eye of the spectator and at right angles to the vertical at a given place; a plane tangent to the earth's surface at that place; called distinctively the sensible horizon.
• The unbroken line separating sky and water, as seen by an eye at a given elevation, no land being visible.
• The epoch or time during which a deposit was made.
• The chief horizontal line in a picture of any sort, which determines in the picture the height of the eye of the spectator; in an extended landscape, the representation of the natural horizon corresponds with this line.
• A plane parallel to the sensible horizon of a place, and passing through the earth's center; - called also rational celestial horizon.
• The circular line where the sky and earth or sea appear to meet; hence, the limit of one's mental vision.
• The circle bounding the view where the earth and sky appear to meet.
• Apparent junction of earth and sky; range of vision.
• The line where the earth or sea seems to meet the sky.
• A circle bounding the view where the earth and sky seem to meet, called the sensible horizon, as distinguished from the great circle parallel to it, the centre of which is the centre of the earth, called the rational horizon.
• The circular line where the earth and sky seem to meet, called the sensible horizon; the great circle dividing the visible and invisible heavens into two equal parts is called the rational horizon.
• [ Greek] Soil layer of a more or less well-defined character; a layer of deposit characterised by definite fossil species and formed at a definite time.

Usage examples for horizon

1. Not when every corner you turn may show you smoke on the horizon?  The Boy With the U. S. Foresters by Francis Rolt-Wheeler

2. Her heart beat warm and true as ever, home and friends were dear as ever, but for a time her horizon was bounded by the narrow walls of one small dark house in the Euston Road.  Elizabeth Gilbert and Her Work for the Blind by Frances Martin

3. Venus- evening star on that date- was sinking to the horizon.  Tarrano the Conqueror by Raymond King Cummings

4. Tod's eyes, blue and deep- set, seemed fixed on the horizon, Malloring's, blue and deep- set, on the nearest thing they could light on.  The Freelands by John Galsworthy