Definition of "altitude"

Like most human activities, ballooning has sponsored heroes and hucksters and a good deal in between. For every dedicated scientist patiently recording atmospheric pressure and wind speed while shivering at high altitudes, there is a carnival barker with a bevy of pretty girls willing to dangle from a basket or parachute down to earth.

2013 June 7, David Simpson, “Fantasy of navigation”, in The Guardian Weekly, volume 188, number 26, page 36

Whoever has an ambition to be heard in a crowd, must press, and squeeze, and thrust, and climb, with indefatigable pains, till he has exalted himself to a certain degree of altitude above them.

1704, [Jonathan Swift], A Tale of a Tub. […], London: […] John Nutt, […]

The man of law began to get into his altitudes.

1815 February 24, [Walter Scott], Guy Mannering; or, The Astrologer. […], volumes (please specify |volume=I to III), Edinburgh: […] James Ballantyne and Co. for Longman, Hurst, Rees, Orme, and Brown, […]; and Archibald Constable and Co., […]

Is this deified passion , in its greatest altitudes , fitted to stand the day ?

1748, [Samuel Richardson], Clarissa. Or, The History of a Young Lady: […], volumes (please specify |volume=I to VII), London: […] S[amuel] Richardson; […]

He is [proud] even to the altitude of his virtue.

c. 1608–1609 (date written), William Shakespeare, “The Tragedy of Coriolanus”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act I, scene i]