\Hor`i*zon"tal\, a. [Cf. F. horizontal.]
1. Pertaining to, or near, the horizon. ``Horizontal misty
   air.'' --Milton.
2. Parallel to the horizon; on a level; as, a horizontalline
   or surface.
3. 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.