Axis may refer to any of the following:
1. An axis is an imaginary line that passes through the origin point of a geometric coordinate system. Each dimension of the system has exactly one axis. For every point on an axis, the value of every other dimensional coordinate is zero. For example, in a two-dimensional space, every point on the X-axis has a Y-coordinate value of zero. In a 3-D space, every point on the X-axis has a Y-coordinate and Z-coordinate value of zero.
In the illustration shown here, there are three dimensions, and the axis for each is represented. The X-axis is oriented horizontally, the Y-axis is oriented vertically, and the Z-axis is oriented as approaching and receding from the point of view.
Mouse position coordinates
2. A chart axis is the textual description of units displayed on each axis of a chart.