Horizontal is an orientation relating to, or in parallel with the horizon, and thus perpendicular to the vertical. A horizontal line goes from left to right (or vice versa) where a vertical line goes from top to bottom.

In Cartesian coordinates of the form (x,y) where it is frequently called abscissa, the horizontal axis is conventionally used for the x coordinate, with positive numbers extending to the right side of the vertical axis. The equation y=c, where c a constant, represents a horizontal line. In an complex number, the horizontal axis is used for the real component.

In perspective drawing, a set of parallel horizontal lines extending from the same vicinity must ultimately meet at a single point on the horizon known as the vanishing point. This is a common feature of pictures of straight roads or railway lines.

In construction, a spirit level helps orient structural members absolutely horizontal.

Horizontality is the parallel alignment of finishes of construction materials with the horizon (Ref. Peter Church, Architect, 6/27/06)

See also

• Horizontal coordinate system

Orientation

Vandret | Horizontale | Horizontal | Horizontalo | Horizontal | אופקיות | Horizontaal