the line or circle that forms the apparent boundary between earth and sky.
2.
Astronomy.
a.
the small circle of the celestial sphere whose plane is tangent to the earth at the position of a given observer, or the plane of such a circle (sensible horizon).
b.
Also called rational horizon.the great circle of the celestial sphere whose plane passes through the center of the earth and is parallel to the sensible horizon of a given position, or the plane of such a circle (celestial horizon).
3.
the limit or range of perception, knowledge, or the like.
4.
Usually, horizons.the scope of a person's interest, education, understanding, etc.: His horizons were narrow.
5.
Geology. a thin, distinctive stratum useful for stratigraphic correlation.
6.
any of the series of distinctive layers found in a vertical cross section of any well-developed soil.
[Origin: 1540–50; < L horizōn < Gk horízōn (kýklos) bounding (circle), equiv. to horíz(ein) to bound, limit + -ōn prp. suffix (nom. sing.); r. ME orizonte < MF < L horizontem, acc. of horizōn]
The apparent intersection of the earth and sky as seen by an observer. Also called apparent horizon.
Astronomy
The sensible horizon.
The celestial horizon.
The limit of the theoretically possible universe.
A specific position in a stratigraphic column, such as the location of one or more fossils, that serves to identify the stratum with a particular period.
A specific layer of soil or subsoil in a vertical cross section of land.
The range of one's knowledge, experience, or interest.
Geology
A specific position in a stratigraphic column, such as the location of one or more fossils, that serves to identify the stratum with a particular period.
A specific layer of soil or subsoil in a vertical cross section of land.
Archaeology A period during which the influence of a specified culture spread rapidly over a defined area: artifacts associated with the Olmec horizon in Mesoamerica.
[Middle English orizon, from Old French, from Latin, from Greek horizōn (kuklos), limiting (circle), horizon, present participle of horizein, to limit, from horos, boundary.]
c.1374, from O.Fr. orizon (14c.), earlier orizonte (13c.), from L. horizontem (nom. horizon), from Gk. horizon kyklos "bounding circle," from horizein "bound, limit, divide, separate," from horos "boundary." The h- was restored 17c. in imitation of Latin. Horizontal (1555) originally meant "relating to or near the horizon," later (1638) parallel to it, "flat."
A specific position in a stratigraphic column, such as the location of one or more fossils, that serves to identify the stratum with a particular period.
A specific layer of soil or subsoil in a vertical cross-section of land.
Geology
A specific position in a stratigraphic column, such as the location of one or more fossils, that serves to identify the stratum with a particular period.
A specific layer of soil or subsoil in a vertical cross-section of land.
Archaeology A period during which the influence of a particular culture spread rapidly over a defined area.
Horizon City, TX (town, FIPS 34832) Location: 31.67008 N, 106.19130 W Population (1990): 2308 (911 housing units) Area: 10.9 sq km (land), 0.0 sq km (water) Zip code(s): 79927
Aph"o*rism\, n. [F. aphorisme, fr. Gr. ? definition, a short, pithy sentence, fr. ? to mark off by boundaries, to define; ? from + ? to separate, part. See Horizon.] A comprehensive maxim or principle expressed in a few words; a sharply defined sentence relating to abstract truth rather than to practical matters. The first aphorism of Hippocrates is, "Life is short, and the art is long." --Fleming. Syn: Axiom; maxim; adage; proverb; apothegm; saying; saw; truism; dictum. See Axiom.
Ar`ti*fi"cial\, a. [L. artificialis, fr. artificium: cf. F. artificiel. See Artifice.]1. Made or contrived by art; produced or modified by human skill and labor, in opposition to natural; as, artificial heat or light, gems, salts, minerals, fountains, flowers. Artificial strife Lives in these touches, livelier than life. --Shak. 2. Feigned; fictitious; assumed; affected; not genuine. "Artificial tears." --Shak. 3. Artful; cunning; crafty. [Obs.] --Shak. 4. Cultivated; not indigenous; not of spontaneous growth; as, artificial grasses. --Gibbon. Artificial arguments (Rhet.), arguments invented by the speaker, in distinction from laws, authorities, and the like, which are called inartificial arguments or proofs. --Johnson. Artificial classification (Science), an arrangement based on superficial characters, and not expressing the true natural relations species; as, "the artificial system" in botany, which is the same as the Linn[ae]an system. Artificial horizon. See under Horizon. Artificial light, any light other than that which proceeds from the heavenly bodies. Artificial lines, lines on a sector or scale, so contrived as to represent the logarithmic sines and tangents, which, by the help of the line of numbers, solve, with tolerable exactness, questions in trigonometry, navigation, etc. Artificial numbers, logarithms. Artificial person (Law). See under Person. Artificial sines, tangents, etc., the same as logarithms of the natural sines, tangents, etc. --Hutton.
Ax"is\, n.; pl. Axes. [L. axis axis, axle. See Axle.] A straight line, real or imaginary, passing through a body, on which it revolves, or may be supposed to revolve; a line passing through a body or system around which the parts are symmetrically arranged. 2. (Math.) A straight line with respect to which the different parts of a magnitude are symmetrically arranged; as, the axis of a cylinder, i. e., the axis of a cone, that is, the straight line joining the vertex and the center of the base; the axis of a circle, any straight line passing through the center. 3. (Bot.) The stem; the central part, or longitudinal support, on which organs or parts are arranged; the central line of any body. --Gray. 4. (Anat.) (a) The second vertebra of the neck, or vertebra dentata. (b) Also used of the body only of the vertebra, which is prolonged anteriorly within the foramen of the first vertebra or atlas, so as to form the odontoid process or peg which serves as a pivot for the atlas and head to turn upon. 5. (Crystallog.) One of several imaginary lines, assumed in describing the position of the planes by which a crystal is bounded. 6. (Fine Arts) The primary or secondary central line of any design. Anticlinal axis (Geol.), a line or ridge from which the strata slope downward on the two opposite sides. Synclinal axis, a line from which the strata slope upward in opposite directions, so as to form a valley. Axis cylinder (Anat.), the neuraxis or essential, central substance of a nerve fiber; -- called also axis band, axial fiber, and cylinder axis. Axis in peritrochio, the wheel and axle, one of the mechanical powers. Axis of a curve (Geom.), a straight line which bisects a system of parallel chords of a curve; called a principal axis, when cutting them at right angles, in which case it divides the curve into two symmetrical portions, as in the parabola, which has one such axis, the ellipse, which has two, or the circle, which has an infinite number. The two axes of the ellipse are the major axis and the minor axis, and the two axes of the hyperbola are the transverse axis and the conjugate axis. Axis of a lens, the straight line passing through its center and perpendicular to its surfaces. Axis of atelescope or microscope, the straight line with which coincide the axes of the several lenses which compose it. Axes of co["o]rdinates in a plane, two straight lines intersecting each other, to which points are referred for the purpose of determining their relative position: they are either rectangular or oblique. Axes of co["o]rdinates in space, the three straight lines in which the co["o]rdinate planes intersect each other. Axis of a balance, that line about which it turns. Axis of oscillation, of a pendulum, a right line passing through the center about which it vibrates, and perpendicular to the plane of vibration. Axis of polarization, the central line around which the prismatic rings or curves are arranged. --Brewster. Axis of revolution (Descriptive Geom.), a straight line about which some line or plane is revolved, so that the several points of the line or plane shall describe circles with their centers in the fixed line, and their planes perpendicular to it, the line describing a surface of revolution, and the plane a solid of revolution. Axis of symmetry (Geom.), any line in a plane figure which divides the figure into two such parts that one part, when folded over along the axis, shall coincide with the other part. Axis of theequator, ecliptic, horizon (or other circle considered with reference to the sphere on which it lies), the diameter of the sphere which is perpendicular to the plane of the circle. --Hutton. Axis of the Ionic capital (Arch.), a line passing perpendicularly through the middle of the eye of the volute. Neutral axis (Mech.), the line of demarcation between the horizontal elastic forces of tension and compression, exerted by the fibers in any cross section of a girder. Optic axis of a crystal, the direction in which a ray of transmitted light suffers no double refraction. All crystals, not of the isometric system, are either uniaxial or biaxial. Optic axis, Visual axis (Opt.), the straight line passing through the center of the pupil, and perpendicular to the surface of the eye. Radical axis of two circles (Geom.), the straight line perpendicular to the line joining their centers and such that the tangents from any point of it to the two circles shall be equal to each other. Spiral axis (Arch.), the axis of a twisted column drawn spirally in order to trace the circumvolutions without. Axis of abscissas and Axis of ordinates. See Abscissa.
Ho*ri"zon\, n. [F., fr. L. horizon, fr. Gr. ? (sc. ?) the bounding line, horizon, fr. ? to bound, fr. ? boundary, limit.]1. The circle 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. (Astron.) (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 or celestial horizon. (c) (Naut.) The unbroken line separating sky and water, as seen by an eye at a given elevation, no land being visible. 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 this line. 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. (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.
O`ris*mol"o*gy\, n. [Gr. ? a marking out by boundaries, the definition of a word + -logy. See Horizon.] That departament of natural history which treats of technical terms.
Quick"sil`ver\, n. [Quick living + silver; -- so called from its fluidity; cf. G. quecksilber, L. argentum vivum. See Quick, a.] (Chem.) The metal mercury; -- so called from its resemblance to liquid silver. Quicksilver horizon, a mercurial artificial horizon. See under Horizon. Quicksilver water, a solution of mercury nitrate used in artificial silvering; quick water.
Ra"tion*al\, a. [L. rationalis: cf. F. rationnel. See Ratio, Reason, and cf. Rationale.]1. Relating to reason; not physical; mental. Moral philosophy was his chiefest end; for the rational, the natural, and mathematics . . . were but simple pastimes in comparison of the other. --Sir T. North. 2. Having reason, or the faculty of reasoning; endowed with reason or understanding; reasoning. It is our glory and happiness to have a rational nature. --Law. 3. Agreeable to reason; not absurd, preposterous, extravagant, foolish, fanciful, or the like; wise; judicious; as, rational conduct; a rational man. 4. (Chem.) Expressing the type, structure, relations, and reactions of a compound; graphic; -- said of formul[ae]. See under Formula. Rational horizon. (Astron.) See Horizon, 2 (b) . Rational quantity (Alg.), one that can be expressed without the use of a radical sign, or in extract parts of unity; -- opposed to irrational or radical quantity. Rational symptom (Med.), one elicited by the statements of the patient himself and not as the result of a physical examination. Syn: Sane; sound; intelligent; reasonable; sensible; wise; discreet; judicious. Usage: Rational, reasonable. Rational has reference to reason as a faculty of the mind, and is opposed to traditional; as, a rational being, a rational state of mind, rational views, etc. In these cases the speculative reason is more particularly, referred to. Reasonable has reference to the exercise of this faculty for practical purposes, and means, governed or directed by reason; as, reasonable prospect of success. What higher in her society thou find'st Attractive, human, rational, love still. --Milton. A law may be reasonable in itself, although a man does not allow it, or does not know the reason of the lawgivers. --Swift.
Sen"si*ble\, a. [F., fr. L. sensibilis, fr. sensus sense.]1. Capable of being perceived by the senses; apprehensible through the bodily organs; hence, also, perceptible to the mind; making an impression upon the sense, reason, or understanding; ?????? heat; sensible resistance. Air is sensible to the touch by its motion. --Arbuthnot. The disgrace was more sensible than the pain. --Sir W. Temple. Any very sensible effect upon the prices of things. --A. Smith. 2. Having the capacity of receiving impressions from external objects; capable of perceiving by the instrumentality of the proper organs; liable to be affected physsically or mentally; impressible. Would your cambric were sensible as your finger. --Shak. 3. Hence: Liable to impression from without; easily affected; having nice perception or acute feeling; sensitive; also, readily moved or affected by natural agents; delicate; as, a sensible thermometer. "With affection wondrous sensible." --Shak. 4. Perceiving or having perception, either by the senses or the mind; cognizant; perceiving so clearly as to be convinced; satisfied; persuaded. He [man] can not think at any time, waking or sleeping, without being sensible of it. --Locke. They are now sensible it would have been better to comply than to refuse. --Addison. 5. Having moral perception; capable of being affected by moral good or evil. 6. Possessing or containing sense or reason; giftedwith, or characterized by, good or common sense; intelligent; wise. Now a sensible man, by and by a fool. --Shak. Sensible note or tone (Mus.), the major seventh note of any scale; -- so called because, being but a half step below the octave, or key tone, and naturally leading up to that, it makes the ear sensible of its approaching sound. Called also the leading tone. Sensible horizon. See Horizon, n., 2. (a) . Syn: Intelligent; wise. Usage: Sensible, Intelligent. We call a man sensible whose judgments and conduct are marked and governed by sound judgment or good common semse. We call one intelligent who is quick and clear in his understanding, i. e., who discriminates readily and nicely in respect to difficult and important distinction. The sphere of the sensible man lies in matters of practical concern; of the intelligent man, in subjects of intellectual interest. "I have been tired with accounts from sensible men, furnished with matters of fact which have happened within their own knowledge." --Addison. "Trace out numerous footsteps . . . of a most wise and intelligent architect throughout all this stupendous fabric." --Woodward.
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