the height of anything above a given planetary reference plane, especially above sea level on earth.

Definition: 2

extent or distance upward; height.

Definition: 3

Astronomy. the angular distance of a heavenly body above the horizon.

Definition: 4

Geometry. the perpendicular distance from the vertex of a figure to the side opposite the vertex. the line through the vertex of a figure perpendicular to the base.

Definition: 5

Usually, altitudes. a high place or region: mountain altitudes.