Axis may refer to any of the following:
1. Alternatively referred to as a coordinate axis an axis is an imaginary line that crosses through a point. In a 3-D environment, there are three axis's as shown in the illustration. In this illustration, you can see an X, Y, and Z-axis, the X-axis is the horizontal axis, the Y-axis is the vertical axis, and the Z-axis is the depth axis. For example, your computer mouse, joystick, and any other pointing devices are a few examples of hardware devices that use an axis to determine where the cursor is shown on the screen.
2. An axis or chart axis is the description of values displayed on the side of a chart that describes the values of what is being displayed.