Source : Webster's Revised Unabridged Dictionary (1913)

Artificial \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.

Horizon \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.

Source : WordNet®

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