Ar·ti·fi·cial a.
 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.”
 3. Artful; cunning; crafty. [Obs.]
 4. Cultivated; not indigenous; not of spontaneous growth; as, artificial grasses.
 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 Linnæan 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.

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 Ho·ri·zon n.
 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. 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 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 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.

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 artificial horizon
      n : a navigational instrument based on a gyroscope; provides an
          artificial horizon for the pilot [syn: gyro horizon, {flight
          indicator]