The word horizontal is derived from the Latin horizon, which derives from the Greek ὁρῐ́ζων, meaning 'separating' or 'marking a boundary'. … See more

Although the word horizontal is commonly used in daily life and language (see below), it is subject to many misconceptions.
• The … See more

• Brennan, David A.; Esplen, Matthew F.; Gray, Jeremy J. (1998), Geometry, Cambridge: Cambridge University Press, ISBN See more

• Video explanations of the terms See more

The plumb line and spirit level
In physics, engineering and construction, the direction designated as vertical is usually that along which a plumb-bob hangs. Alternatively, a See more

In two dimensions
In the context of a 1-dimensional orthogonal Cartesian coordinate system on a Euclidean plane, to say that a line is horizontal or vertical, an initial designation has to be made. One can start off by designating the … See more

• Cartesian coordinate system
• Coordinate system
• Horizon
• Horizontal angle
• Horizontal coordinate system See more