1 Space extended upward; height; the perpendicular elevation of an object above its foundation, above the ground, or above a given level, or of one object above another; as, the altitude of a mountain, or of a bird above the top of a tree.

2 (Astron.)

The elevation of a point, or star, or other celestial object, above the horizon, measured by the arc of a vertical circle intercepted between such point and the horizon. It is either true or apparent; true when measured from the rational or real horizon, apparent when from the sensible or apparent horizon.

3 (Geom.)

The perpendicular distance from the base of a figure to the summit, or to the side parallel to the base; as, the altitude of a triangle, pyramid, parallelogram, frustum, etc.

4 Height of degree; highest point or degree. He is [proud] even to the altitude of his virtue. Shak.

5 Height of rank or excellence; superiority. Swift.

6 pl.

Elevation of spirits; heroics; haughty airs. [Colloq.] Richardson. The man of law began to get into his altitude. Sir W. Scott. Meridian altitude, an arc of the meridian intercepted between the south point on the horizon and any point on the meridian. See Meridian, 3.