noun (n)

• elevation especially above sea level or above the earth's surface(noun.attribute)

  Example:
  The altitude gave her a headache.
  

  Synonym:
  height
  

  source: wordnet30
• the perpendicular distance from the base of a geometric figure to the opposite vertex (or side if parallel)(noun.shape)

  source: wordnet30
• angular distance above the horizon (especially of a celestial object)(noun.linkdef)

  Synonym:
  alt, el, elevation
  

  source: wordnet30
• 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.(noun)

  source: webster1913