[syn: horizon, celestial horizon]
The Collaborative International Dictionary of English v.0.48:
Horizon \Ho*ri"zon\, n. [F., fr. L. horizon, fr. Gr. ? (sc. ?)
the bounding line, horizon, fr. ? to bound, fr. ? boundary,
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.
(a) 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.
(b) A plane parallel to the sensible horizon of a place,
and passing through the earth's center; -- called also
rational horizon or celestial horizon.
(c) (Naut.) The unbroken line separating sky and water, as
seen by an eye at a given elevation, no land being
3. (Geol.) The epoch or time during which a deposit was made.
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. (Painting) 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
5. The limit of a person's range of perception, capabilities,
or experience; as, children raised in the inner city have
6. [fig.] 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.
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
Celestial horizon. (Astron.) See def. 2, above.
Dip of the horizon (Astron.), the vertical angle between
the sensible horizon and a line to the visible horizon,
the latter always being below the former.
Rational horizon, and Sensible horizon. (Astron.) See
def. 2, above.
Visible horizon. See definitions 1 and 2, above.
WordNet (r) 3.0 (2006):
n 1: the line at which the sky and Earth appear to meet [syn:
horizon, apparent horizon, visible horizon, sensible
2: the range of interest or activity that can be anticipated;
"It is beyond the horizon of present knowledge" [syn:
horizon, view, purview]
3: a specific layer or stratum of soil or subsoil in a vertical
cross section of land
4: the great circle on the celestial sphere whose plane passes
through the sensible horizon and the center of the Earth
[syn: horizon, celestial horizon]
Moby Thesaurus II by Grady Ward, 1.0:
71 Moby Thesaurus words for "horizon":
azimuth, background, clear sight, color vision, command, compass,
cone vision, day vision, daylight vision, discernment, domination,
eye, eye-mindedness, eyereach, eyeshot, eyesight, false horizon,
farsight, farsightedness, field of view, field of vision,
keen sight, ken, limit of vision, limits, line of sight, naked eye,
night vision, offing, outlook, outlook over, perception,
peripheral field, peripheral vision, perspective, perspicacity,
perspicuity, photopia, power of sight, prospect, purview,
quick sight, range, reach, remote distance, rod vision, scan,
scope, scope of vision, scotopia, sea line, seeing, sense of sight,
sensible horizon, sight, sightedness, sightliness, skyline, survey,
sweep, the distance, twilight vision, unobstructed vision,
vanishing point, view, visible horizon, vision, vista,
visual acuity, visual field, visual sense