z axis

/ˈziː ˌæksɪs/
noun
  1. In a three-dimensional coordinate system, the axis that is perpendicular to both the x-axis and y-axis, often representing depth or height.
    • When plotting points in space, the z-axis measures depth.
    • In 3D modeling, you can move an object along the z-axis to make it appear closer or farther away.
    • The z-axis on a graph usually shows the vertical dimension.