rational horizon
Horizon Ho*ri"zon, n. [F., fr. L. horizon, fr. Gr. ? (sc. ?) the bounding line, horizon, fr. ? to bound, fr. ? boundary, limit.] 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. [1913 Webster]

And when the morning sun shall raise his car Above the border of this horizon. --Shak. [1913 Webster]

All the horizon round Invested with bright rays. --Milton. [1913 Webster]

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. [1913 Webster]

3. (Geol.) The epoch or time during which a deposit was made. [1913 Webster]

The strata all over the earth, which were formed at the same time, are said to belong to the same geological horizon. --Le Conte. [1913 Webster]

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. [1913 Webster]

5. The limit of a person's range of perception, capabilities, or experience; as, children raised in the inner city have limited horizons. [PJC]

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. [PJC]

{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. [1913 Webster]


The Collaborative International Dictionary of English. 2000.

Look at other dictionaries:

  • Rational horizon — Horizon Ho*ri zon, n. [F., fr. L. horizon, fr. Gr. ? (sc. ?) the bounding line, horizon, fr. ? to bound, fr. ? boundary, limit.] 1. The line which bounds that part of the earth s surface visible to a spectator from a given point; the apparent… …   The Collaborative International Dictionary of English

  • Rational horizon — Rational Ra tion*al (r[a^]sh [u^]n*al), a. [L. rationalis: cf. F. rationnel. See {Ratio}, {Reason}, and cf. {Rationale}.] 1. Relating to the reason; not physical; mental. [1913 Webster] Moral philosophy was his chiefest end; for the rational, the …   The Collaborative International Dictionary of English

  • rational horizon — noun : horizon 1b(1), 1b(2) * * * rational horizon see under ↑horizon • • • Main Entry: ↑rational …   Useful english dictionary

  • RATIONAL HORIZON —    a great circle parallel to the horizon, the centre of which is the centre of the earth …   The Nuttall Encyclopaedia

  • Rational — Ra tion*al (r[a^]sh [u^]n*al), a. [L. rationalis: cf. F. rationnel. See {Ratio}, {Reason}, and cf. {Rationale}.] 1. Relating to the reason; not physical; mental. [1913 Webster] Moral philosophy was his chiefest end; for the rational, the natural …   The Collaborative International Dictionary of English

  • Rational quantity — Rational Ra tion*al (r[a^]sh [u^]n*al), a. [L. rationalis: cf. F. rationnel. See {Ratio}, {Reason}, and cf. {Rationale}.] 1. Relating to the reason; not physical; mental. [1913 Webster] Moral philosophy was his chiefest end; for the rational, the …   The Collaborative International Dictionary of English

  • Rational symptom — Rational Ra tion*al (r[a^]sh [u^]n*al), a. [L. rationalis: cf. F. rationnel. See {Ratio}, {Reason}, and cf. {Rationale}.] 1. Relating to the reason; not physical; mental. [1913 Webster] Moral philosophy was his chiefest end; for the rational, the …   The Collaborative International Dictionary of English

  • Horizon — Ho*ri zon, n. [F., fr. L. horizon, fr. Gr. ? (sc. ?) the bounding line, horizon, fr. ? to bound, fr. ? boundary, limit.] 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 Collaborative International Dictionary of English

  • rational — adj. 1 of or based on reasoning or reason. 2 sensible, sane, moderate; not foolish or absurd or extreme. 3 endowed with reason, reasoning. 4 rejecting what is unreasonable or cannot be tested by reason in religion or custom. 5 Math. (of a… …   Useful english dictionary

  • horizon — i. In general, the apparent or visible junction of the earth and sky, as seen from any specific position. Also called a visible or local horizon. ii. When an apparent boundary is modified by refraction, terrain, or other factors, it is called an… …   Aviation dictionary

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