red·out
(rĕd′out′)n. A sudden reddening of the visual field accompanied by severe headache and caused by engorgement of the blood vessels of the head when a person is subjected to a negative force of gravity, as in stunt flying.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
redout
(ˈrɛdˌaʊt) nreddened vision and other symptoms caused by a rush of blood to the head in response to negative gravitational stresses
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
red•out
(ˈrɛdˌaʊt)
n. a condition experienced by pilots and astronauts in which rapid deceleration or a negative gravity force drives blood to the head, reddening the field of vision.
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