a garment worn by astronauts and high-speed pilots to avoid blackouts during rapid acceleration: it exerts pressure on the abdomen and legs to prevent the pooling of blood away from the heart and brain
See G-suit in American Heritage Dictionary 4
(jēˈso͞otˌ)
noun
A flight garment worn by astronauts and jet pilots that presses on the lower body to maintain the blood supply to the brain during rapid vertical acceleration.