elevation especially above sea level or above the earth's surface
The altitude gave her a headache.
source: WordNet 3.0
the perpendicular distance from the base of a geometric figure to the opposite vertex (or side if parallel)
source: WordNet 3.0
angular distance above the horizon (especially of a celestial object)
source: WordNet 3.0
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.
