The Collaborative International Dictionary
G suit \G suit\ G-suit \G-suit\ n. [gravity + suit. 1944[MW10]] (Aeronautics) A suit worn by aviators and astronauts, designed to counteract the effects of high accelerations experienced in aerial maneuvers, in particular to avoid unconsciousness; called also anti-g suit. It exerts force on the abdomen and legs to prevent blackouts by counteracting the tendency of blood to accumulate below the heart, thus reducing the supply to the brain, when the forces due to acceleration are directed from head to toe.
Wiktionary
n. A suit designed to maintain the supply of blood to the head during violent acceleration
Wikipedia
A g-suit, or the more accurately named anti-g suit, is a flight suit worn by aviators and astronauts who are subject to high levels of acceleration force ( g). It is designed to prevent a black-out and g-LOC ( g-induced loss of consciousness) caused by the blood pooling in the lower part of the body when under acceleration, thus depriving the brain of blood. Black-out and g-LOC has caused a number of fatal aircraft accidents.
Usage examples of "g-suit".
With our wraith-hides, inner-skin g-suits, wraith-gut air bags, lower-intestine air hoses, bone spears, my plasma rifle, packs, and claw-skis, we must have looked like some Old Earth Paleolithic astronauts.
Flap said as he tucked Malcolm X into his G-suit pocket and zipped it shut.