redout

red +‎ out, because it may cause a red appearance in the visual field; compare blackout.

redout (plural redouts)

1. The situation where the body experiences a negative g-force sufficient to cause a blood flow from the lower parts of the body to the head.
   • 1994, Geza Szurovy, Basic Aerobatics, page 34:

     The heart is unable to sufficiently regulate blood flow to prevent excess blood from flooding the brain's blood vessels and causing redout.

• grayout, greyout

redout (plural redouts)

1. Alternative form of redoubt (military fortification)
   • 1913, Gustave Joseph Fiebeger, A text-book on field fortification, page 44:

     The entrances to the works through the gorge are protected by the traverses G. Closed fieldworks of this type usually designed for defense by one or two companies of infantry with machine guns are called redouts.

• detour, douter, routed, toured