A collection of symptoms, including shortness of breath, headache, and nosebleed, brought on by decreased oxygen in the atmosphere, such as that encountered at high altitudes.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.