The Collaborative International Dictionary
Horizontal \Hor`i*zon"tal\, a. [Cf. F. horizontal.]
Pertaining to, or near, the horizon. ``Horizontal misty air.''
--Milton.Parallel to the horizon; on a level; as, a horizontalline or surface.
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Measured or contained in a plane of the horizon; as, horizontal distance.
Horizontal drill, a drilling machine having a horizontal drill spindle.
Horizontal engine, one the piston of which works horizontally.
Horizontal fire (Mil.), the fire of ordnance and small arms at point-blank range or at low angles of elevation.
Horizontal force (Physics), the horizontal component of the earth's magnetic force.
Horizontal line (Descriptive Geometry & Drawing), a constructive line, either drawn or imagined, which passes through the point of sight, and is the chief line in the projection upon which all verticals are fixed, and upon which all vanishing points are found.
Horizontal parallax. See under Parallax.
Horizontal plane (Descriptive Geometry), a plane parallel to the horizon, upon which it is assumed that objects are projected. See Projection. It is upon the horizontal plane that the ground plan of the buildings is supposed to be drawn.
Horizontal projection, a projection made on a plane parallel to the horizon.
Horizontal range (Gunnery), the distance in a horizontal plane to which a gun will throw a projectile.
Horizontal water wheel, a water wheel in which the axis is vertical, the buckets or floats revolving in a horizontal plane, as in most turbines.
Wikipedia
In geometry, physics, astronomy, geography, and related sciences, a plane is said to be horizontal at a given point if it is perpendicular to the gradient of the gravity field at that point— in other words, if apparent gravity makes a plumb bob hang perpendicular to the plane at that point. Alternatively, a spirit level, which exploits the buoyancy of a bubble, can be used to determine if the plane is horizontal.
In radio science, horizontal plane is used to plot an antenna's relative field strength in relation to the ground (which directly affects a station's coverage area) on a polar graph. Normally the maximum of 1.000 or 0 dB is at the top, which is labeled 0, running clockwise back around to the top at 360°. Other field strengths are expressed as a decimal less than 1.000, a percentage less than 100%, or decibels less than 0 dB. If the graph is of an actual or proposed installation, rotation is applied so that the top is 0 true north. See also the perpendicular vertical plane.
In general, something that is horizontal can be drawn from left to right (or right to left), such as the x-axis in the Cartesian coordinate system.
Usage examples of "horizontal plane".
It is also always developed with the flat lower side, which, as just stated, forms a part of the radicle, at right angles to it, and in a horizontal plane.
It moved easily, pivoting in a horizontal plane until it was perpendicular to the tunnel.
The optical landing system was stabilized in pitch and roll, that is, in the horizontal plane, but it could not compensate for instability in the vertical plane, the up-and-down motion of the ship known as heave.
He caught the movement now, this time soundless, along the horizontal plane of the fire escape one flight-up.
Because, as the physical being-there of a bed or horizontal plane determines what we call love.
They are all inclined to the horizontal plane of the Pyramid and their angles of slope vary from 32 degrees 28 minutes (northern shaft of the King’.
It was directly above Jack's machine and descending on a horizontal plane.
Peculiarly out of kilter with the rest of the ship, the bridge stood on a perfect horizontal plane.
Now the President's head re-formed, facing her on the horizontal plane.
At the same moment, a powerful current rolled across the slope, sweeping the sand into small swirling clouds, stretching the weed growth on a wavering horizontal plane.
The top end of the bar broke loose, bending its jagged and torn tip inward until it lay on a horizontal plane.
Paolo was to his rear-left-dexter-gauche, and he turned first in the horizontal plane, then the hyperal.