al·ti·tude (ăltĭ-td′, -tyd′)
a. The height of a thing above a reference level, especially above sea level or above the earth's surface. See Synonyms at elevation.
b. Great height or elevation: has trouble breathing at altitude.
c. often altitudes A high location or area.
2. Astronomy The angular distance above the observer's horizon of a celestial object.
3. Mathematics The perpendicular distance from the base of a geometric figure to the opposite vertex, parallel side, or parallel surface.
[Middle English, from Latin altitūdō, from altus, high; see al-2 in the Appendix of Indo-European roots.]
al′ti·tudi·nal (-tdn-əl, -tyd-) adj.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The American Heritage Dictionary Blog
Check out our blog, updated regularly, for new words and revised definitions, interesting images from the 5th edition, discussions of usage, and more.