Horizon — Defs

01 n. The line which bounds that part of the earth's surface visible to a spectator from a given point; the apparent junction of the earth and sky.

1.
The line which bounds that part of the earth's surface visible to a spectator from a given point; the apparent junction of the earth and sky.
“And when the morning sun shall raise his car Above the border of this horizon.” — Shak.

“All the horizon round Invested with bright rays.” — Milton.
2.
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.(Astron.)
3.
The epoch or time during which a deposit was made.(Geol.)
“The strata all over the earth, which were formed at the same time, are said to belong to the same geological horizon.” — Le Conte.
4.
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.(Painting)
5.
The limit of a person's range of perception, capabilities, or experience; as, children raised in the inner city have limited horizons.
6.
A boundary point or line, or a time point, beyond which new knowledge or experiences may be found; as, more powerful computers are just over the horizon.[fig.]

Phrases & compounds

Apparent horizon — See under Apparent.

Artificial horizon — a level mirror, as the surface of mercury in a shallow vessel, or a plane reflector adjusted to the true level artificially; -- used chiefly with the sextant for observing the double altitude of a celestial body.

Celestial horizon — See def. 2, above.

Dip of the horizon — the vertical angle between the sensible horizon and a line to the visible horizon, the latter always being below the former.

Rational horizon — See def. 2, above.

Visible horizon — See definitions 1 and 2, above.